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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 5.0L and 5.7L > DTC P0420 Catalyst System Low Efficiency Bank 1 (Over 8600 GVW (C6P))
DTC P0420 Catalyst System Low Efficiency Bank 1 (Over 8600 GVW (C6P))
|NOTE |
|Applicable vehicles: |
|Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) |
DTC P0420 Catalyst System Low Efficiency Bank 1 (Over 8600 GVW (C6P))
|[pic] |
| |
|Click to Enlarge |
Circuit Description
This diagnostic test is designed in order to measure the efficiency of the three-way catalytic converter (TWC) system. Catalytic convertor efficiency is a measure of its ability to store oxygen after converting the levels of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) to less harmful gases. The control module is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of the steady cruise speeds used in the past.
Once the conditions for running this diagnostic trouble code (DTC) are met, the control module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The control module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.
For example, if the control module were to command a rich mixture, the upstream heated oxygen sensor (HO2S) voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream oxygen (O2) sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.
Conditions for Running the DTC
• No active secondary AIR DTCs
• No active CMP sensor DTCs
• No active ECT sensor DTCs
• No active EGR DTCs
• No active fuel trim DTCs
• No active IAC DTCs
• No active IAT sensor DTCs
• No active MAF sensor DTCs
• No active MAP sensor DTCs
• No active O2 sensor DTCs
• No active transmission DTCs
• No active EVAP system DTCs
• No active TP sensor DTCs
• No active VS sensor DTCs
• No active misfire DTCs
• The engine speed is 1,000 RPM or more for more than 40 seconds since last idle period
• The engine has been running for at least 360 seconds and the long term fuel trim is stable
• The predicted catalyst temperature is at least 390°C (734°F)
• The system is in closed loop
• The BARO is 73 kPa or more
• The IAT is between -7-117°C (20°-167° F)
• The ECT is between 75-117°C (167-243° F)
• The engine has been idling for less than 120 seconds
• The actual engine speed is within 100 RPM of the desired idle speed
Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
• The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The use of fuel with a high sulfur or lead content can degrade a marginal converter's performance. Be sure to check fuel quality.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the three-way catalytic converter efficiency to appear degraded. Inspect and repair exhaust system as necessary. Refer to Exhaust System Inspection in Engine Exhaust.
6. Before the three-way catalytic converter is replaced, make sure that the following conditions are not present:
o Misfire
o High engine oil consumption or coolant consumption
o Retarded spark timing or weak spark
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool Capture Info| | |(OBD) System Check |
| |to save the Freeze Frame and Failure Records for reference. The | | | |
| |control module's data is deleted once the Clear Info function is | | | |
| |used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Are any other DTCs set? |-- |Go to the |Go to Step 3 |
| | | |applicable DTC | |
| | | |table | |
|3 |Check the exhaust system for the following conditions: |-- |Go to Step 5 |Go to Step 4 |
| |Leaks | | | |
| |Loose or missing hardware | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|4 |Verify that the correct original equipment three-way catalytic |-- |Go to Step 5 |Go to Step 6 |
| |converter is installed. | | | |
| |Check the converter for the following: | | | |
| |Dents | | | |
| |Severe discoloration | | | |
| |Holes | | | |
| |Ensure that the oxygen sensors are properly installed and that the | | | |
| |wiring connections are properly retained and not damaged. | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|5 |Using the scan tool, clear the DTCs. |-- |System OK |Go to Step 6 |
| |Start the engine. | | | |
| |Allow the engine to idle until the engine reaches normal operating | | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number which was set. | | | |
| |Operate the vehicle, with the Conditions for Setting this DTC, | | | |
| |until the scan tool indicates the diagnostic Ran. | | | |
| |Does the scan tool indicate the diagnostic Passed? | | | |
|6 |NOTE |-- |System OK |-- |
| | | | | |
| |Notice: In order to avoid damaging the replacement three-way | | | |
| |catalytic converter, correct the engine misfire or mechanical fault| | | |
| |before replacing the three-way catalytic converter. | | | |
| | | | | |
| |Replace the catalytic converter. Refer to Catalytic Converter | | | |
| |Replacement in Engine Exhaust. | | | |
| |Is the action complete? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 5.0L and 5.7L > DTC P0420 Catalyst System Low Efficiency Bank 1 (Under 8600 GVW (Without C6P))
DTC P0420 Catalyst System Low Efficiency Bank 1 (Under 8600 GVW (Without C6P))
|NOTE |
|Applicable vehicles: |
|Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) |
DTC P0420 Catalyst System Low Efficiency Bank 1 (Under 8600 GVW (without C6P))
|[pic] |
| |
|Click to Enlarge |
Circuit Description
This diagnostic test is designed in order to measure the efficiency of the three-way catalytic converter (TWC) system. Catalytic convertor efficiency is a measure of its ability to store oxygen after converting the levels of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) to less harmful gases. The control module is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of the steady cruise speeds used in the past.
Once the conditions for running this diagnostic trouble code (DTC) are met, the control module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The control module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.
For example, if the control module were to command a rich mixture, the upstream heated oxygen sensor (HO2S) voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream oxygen (O2) sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.
Conditions for Running the DTC
• No active secondary AIR DTCs
• No active CMP sensor DTCs
• No active ECT sensor DTCs
• No active EGR DTCs
• No active fuel trim DTCs
• No active IAC DTCs
• No active IAT sensor DTCs
• No active MAF sensor DTCs
• No active MAP sensor DTCs
• No active O2 sensor DTCs
• No active transmission DTCs
• No active EVAP system DTCs
• No active TP sensor DTCs
• No active VS sensor DTCs
• No active misfire DTCs
• The engine speed is 1,000 RPM or more for more than 40 seconds since last idle period
• The engine has been running for at least 360 seconds and the long term fuel trim is stable
• The predicted catalyst temperature is at least 390°C (734°F)
• The system is in closed loop
• The BARO is 73 kPa or more
• The IAT is between -7-117°C (20-167° F)
• The ECT is between 75-117°C (167-243° F)
• The engine has been idling for less than 120 seconds
• The actual engine speed is within 100 RPM of the desired idle speed
Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
• The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The use of fuel with a high sulfur or lead content can degrade a marginal converter's performance. Be sure to check fuel quality.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the three-way catalytic converter efficiency to appear degraded. Inspect and repair exhaust system as necessary. Refer to Exhaust System Inspection in Engine Exhaust.
6. Before the three-way catalytic converter is replaced, make sure that the following conditions are not present:
o Misfire
o High engine oil consumption or coolant consumption
o Retarded spark timing or weak spark
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool Capture Info| | |(OBD) System Check |
| |to save the Freeze Frame and Failure Records for reference. The | | | |
| |control module's data is deleted once the Clear Info function is | | | |
| |used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Are any other DTCs set? |-- |Go to the |Go to Step 3 |
| | | |applicable DTC | |
| | | |table | |
|3 |Check the exhaust system for the following conditions: |-- |Go to Step 5 |Go to Step 4 |
| |Leaks | | | |
| |Loose or missing hardware | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|4 |Verify that the correct original equipment three-way catalytic |-- |Go to Step 5 |Go to Step 6 |
| |converter is installed. | | | |
| |Check the converter for the following: | | | |
| |Dents | | | |
| |Severe discoloration | | | |
| |Holes | | | |
| |Ensure that the oxygen sensors are properly installed and that the | | | |
| |wiring connections are properly retained and not damaged. | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|5 |Using the scan tool, clear the DTCs. |-- |System OK |Go to Step 6 |
| |Start the engine. | | | |
| |Allow the engine to idle until the engine reaches normal operating | | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number which was set. | | | |
| |Operate the vehicle, with the Conditions for Setting this DTC, | | | |
| |until the scan tool indicates the diagnostic Ran. | | | |
| |Does the scan tool indicate the diagnostic Passed? | | | |
|6 |NOTE |-- |System OK |-- |
| | | | | |
| |Notice: In order to avoid damaging the replacement three-way | | | |
| |catalytic converter, correct the engine misfire or mechanical fault| | | |
| |before replacing the three-way catalytic converter. | | | |
| | | | | |
| |Replace the catalytic converter. Refer to Catalytic Converter | | | |
| |Replacement in Engine Exhaust. | | | |
| |Is the action complete? | | | |
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 5.0L and 5.7L > DTC P0420 Catalyst System Low Efficiency Bank 1 (Single Exhaust)
DTC P0420 Catalyst System Low Efficiency Bank 1 (Single Exhaust)
|NOTE |
|Applicable vehicles: |
|Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) |
DTC P0420 Catalyst System Low Efficiency Bank 1 (Single Exhaust)
|[pic] |
| |
|Click to Enlarge |
Circuit Description
This diagnostic test is designed in order to measure the efficiency of the three-way catalytic converter (TWC) system. Catalytic convertor efficiency is a measure of its ability to store oxygen after converting the levels of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) to less harmful gases. The control module is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of the steady cruise speeds used in the past.
Once the conditions for running this diagnostic trouble code (DTC) are met, the control module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The control module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.
For example, if the control module were to command a rich mixture, the upstream heated oxygen sensor (HO2S) voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream oxygen (O2) sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.
Conditions for Running the DTC
• No active secondary AIR DTCs
• No active CMP sensor DTCs
• No active ECT sensor DTCs
• No active EGR DTCs
• No active fuel trim DTCs
• No active IAC DTCs
• No active IAT sensor DTCs
• No active MAF sensor DTCs
• No active MAP sensor DTCs
• No active O2 sensor DTCs
• No active transmission DTCs
• No active EVAP system DTCs
• No active TP sensor DTCs
• No active VS sensor DTCs
• No active misfire DTCs
• The engine speed is 1,000 RPM or more for more than 40 seconds since last idle period
• The engine has been running for at least 360 seconds and the long term fuel trim is stable
• The predicted catalyst temperature is at least 390°C (734°F)
• The system is in closed loop
• The BARO is 73 kPa or more
• The IAT is between -7-117°C (20°-167° F)
• The ECT is between 75-117°C (167-243° F)
• The engine has been idling for less than 120 seconds
• The actual engine speed is within 100 RPM of the desired idle speed
Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
• The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The use of fuel with a high sulfur or lead content can degrade a marginal converter's performance. Be sure to check fuel quality.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the three-way catalytic converter efficiency to appear degraded. Inspect and repair exhaust system as necessary. Refer to Exhaust System Inspection in Engine Exhaust.
6. Before the three-way catalytic converter is replaced, make sure that the following conditions are not present:
o Misfire
o High engine oil consumption or coolant consumption
o Retarded spark timing or weak spark
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool Capture Info| | |(OBD) System Check |
| |to save the Freeze Frame and Failure Records for reference. The | | | |
| |control module's data is deleted once the Clear Info function is | | | |
| |used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Are any other DTCs set? |-- |Go to the |Go to Step 3 |
| | | |applicable DTC | |
| | | |table | |
|3 |Check the exhaust system for the following conditions: |-- |Go to Step 5 |Go to Step 4 |
| |Leaks | | | |
| |Loose or missing hardware | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|4 |Verify that the correct original equipment three-way catalytic |-- |Go to Step 5 |Go to Step 6 |
| |converter is installed. | | | |
| |Check the converter for the following: | | | |
| |Dents | | | |
| |Severe discoloration | | | |
| |Holes | | | |
| |Ensure that the oxygen sensors are properly installed and that the | | | |
| |wiring connections are properly retained and not damaged. | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|5 |Using the scan tool, clear the DTCs. |-- |System OK |Go to Step 6 |
| |Start the engine. | | | |
| |Allow the engine to idle until the engine reaches normal operating | | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number which was set. | | | |
| |Operate the vehicle, with the Conditions for Setting this DTC, | | | |
| |until the scan tool indicates the diagnostic Ran. | | | |
| |Does the scan tool indicate the diagnostic Passed? | | | |
|6 |NOTE |-- |System OK |-- |
| | | | | |
| |Notice: In order to avoid damaging the replacement three-way | | | |
| |catalytic converter, correct the engine misfire or mechanical fault| | | |
| |before replacing the three-way catalytic converter. | | | |
| | | | | |
| |Replace the catalytic converter. Refer to Catalytic Converter | | | |
| |Replacement in Engine Exhaust. | | | |
| |Is the action complete? | | | |
Bottom of Form
|Trouble Code: P0420 (5.7L V8 VIN R Auto) |Print this code data[pic] |
|Catalyst System Low Efficiency (Bank 1) | |
Number of Trips to Set Code: 1
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• CAT Details
• MIL Details
Trouble Code Conditions:
DTC P0101-P0103, P0106-P0108, P0112, P0113, P0117, P0118, P0125, P0131, P0132-P0138, P0140, P0141, P0151-P0158, P0160, P0161, P0171-P0175, P0200, P0300, P0325, P0327, P0335, P0336, P0341, P0343, P0351-P0358, P0443-P0449, P0502, P0503, P0506, P0507, P1120, P1125, P1133, P1134, P1153, P1154, P1220, P1221, P1275, P1276, P1280-P1286, P1441, P1514, P1518 not set, engine started, engine runtime over 6 minutes, engine speed over 1000 rpm for 32-40 since last idle period, BARO sensor over 72 kPa, ECT sensor more than 167ºF, IAT sensor over 16ºF, MAF sensor from 15-50 g/sec, Catalyst Temperature over 840ºF, engine running at idle speed for under 2 minutes with the Actual idle speed within 100-125 rpm of the Desired idle speed, then vehicle driven to 22-85 mph in closed loop, TP angle over 2% on 7.4L V8, Long Term fuel trim stable, any change in engine load less than 10%, and the PCM detected the Bank 1 Catalyst was degraded.
Possible Causes:
• Air leaks at the exhaust manifold or in the exhaust pipes
• Base engine problems (i.e., high engine oil or coolant usage)
• Catalytic converter is damaged, contaminated or has failed
• Continuous engine misfire conditions, or weak or low coil output
• Front HO2S or rear HO2S is contaminated with fuel or moisture
• Rear HO2S is loose in the mounting hole (check it for a leak)
• Front HO2S older (aged) than the rear HO2S (HO2S-12 is lazy)
• TSB 81-65-37 contains a repair procedure for this code
1998 GMC C1500 Suburban - Powertrain - Engine Controls - 5.0L and 5.7L - DTC P0420 Catalyst System Low Efficiency Bank 1 (Over 8600 GVW (C6P))1998 GMC C1500 Suburban - Powertrain - Engine Controls - 5.0L and 5.7L - DTC P0420 Catalyst System Low Efficiency Bank 1 (Single Exhaust)1998 GMC C1500 Suburban - Powertrain - Engine Controls - 5.0L and 5.7L - DTC P0420 Catalyst System Low Efficiency Bank 1 (Under 8600 GVW (Without C6P))
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 5.0L and 5.7L > DTC P0430 Catalyst System Low Efficiency Bank 2 (Over 8600 GVW C6P)
DTC P0430 Catalyst System Low Efficiency Bank 2 (Over 8600 GVW C6P)
|NOTE |
|Applicable vehicles: |
|Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) |
DTC P0430 Catalyst System Low Efficiency Bank 2 (Over 8600 GVW C6P)
|[pic] |
| |
|Click to Enlarge |
Circuit Description
This diagnostic test is designed in order to measure the efficiency of the three-way catalytic converter (TWC) system. Catalytic convertor efficiency is a measure of its ability to store oxygen after converting the levels of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) to less harmful gases. The control module is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of the steady cruise speeds used in the past.
Once the conditions for running this diagnostic trouble code (DTC) are met, the control module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The control module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.
For example, if the control module were to command a rich mixture, the upstream heated oxygen sensor (HO2S) voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream oxygen (O2) sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.
Conditions for Running the DTC
• No active secondary AIR DTCs
• No active CMP sensor DTCs
• No active ECT sensor DTCs
• No active EGR DTCs
• No active fuel trim DTCs
• No active IAC DTCs
• No active IAT sensor DTCs
• No active MAF sensor DTCs
• No active MAP sensor DTCs
• No active O2 sensor DTCs
• No active transmission DTCs
• No active EVAP system DTCs
• No active TP sensor DTCs
• No active VS sensor DTCs
• No active misfire DTCs
• The engine speed is 1,000 RPM or more for more than 40 seconds since last idle period
• The engine has been running for at least 360 seconds and the long term fuel trim is stable
• The predicted catalyst temperature is at least 390°C (734°F)
• The system is in closed loop
• The BARO is 73 kPa or more
• The IAT is between -7-117°C (20°-167° F)
• The ECT is between 75-117°C (167-243° F)
• The engine has been idling for less than 120 seconds
• The actual engine speed is within 100 RPM of the desired idle speed
Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
• The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The use of fuel with a high sulphur or lead content can degrade a marginal converter's performance. Be sure to check the fuel quality.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the three-way catalytic converter efficiency to appear degraded. Inspect and repair exhaust system as necessary. Refer to Exhaust System Inspection
6. Before the three-way catalytic converter is replaced, make sure that the following conditions are not present:
o Misfire
o High engine oil consumption or coolant consumption
o Retarded spark timing or weak spark
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool Capture Info| | |(OBD) System Check |
| |to save the Freeze Frame and Failure Records for reference. The | | | |
| |control module's data is deleted once the Clear Info function is | | | |
| |used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Are any other DTCs set? |-- |Go to the |Go to Step 3 |
| | | |applicable DTC | |
| | | |table | |
|3 |Check exhaust system for the following: |-- |Go to Step 5 |Go to Step 4 |
| |Leaks | | | |
| |Loose or missing hardware | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|4 |Verify that the correct original equipment three-way catalytic |-- |Go to Step 5 |Go to Step 6 |
| |converter is installed. | | | |
| |Check the converter for the following: | | | |
| |Dents | | | |
| |Severe discoloration | | | |
| |Holes | | | |
| |Ensure that the oxygen sensors are properly installed and that the | | | |
| |wiring connections are properly retained and not damaged. | | | |
| |Repair as necessary. Refer to Exhaust System Inspection . | | | |
| |Did you find a problem? | | | |
|5 |Using the scan tool, clear the DTCs. |-- |System OK |Go to Step 6 |
| |Start the engine. | | | |
| |Allow the engine to idle until the engine reaches normal operating | | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number that was set. | | | |
| |Operate the vehicle, within the Conditions for Setting this DTC, | | | |
| |until the Scan Tool indicates the diagnostic Ran. | | | |
| |Does the Scan tool indicate the diagnostic Passed? | | | |
|6 |NOTE |-- |System OK |-- |
| | | | | |
| |Notice: In order to avoid damaging the replacement three-way | | | |
| |catalytic converter, correct the engine misfire or mechanical fault| | | |
| |before replacing the three-way catalytic converter. | | | |
| | | | | |
| |Replace the catalytic converter. Refer to Catalytic Converter | | | |
| |Replacement in Engine Exhaust. | | | |
| |Is the action complete? | | | |
Bottom of Form
Top of Form
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[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 5.0L and 5.7L > DTC P0430 Catalyst System Low Efficiency Bank 2 (Under 8600 GVW without C6P)
DTC P0430 Catalyst System Low Efficiency Bank 2 (Under 8600 GVW without C6P)
|NOTE |
|Applicable vehicles: |
|Chevy Pickup, GMC Pickup, Suburban, Tahoe, Yukon (VIN C/K) |
DTC P0430 Catalyst System Low Efficiency Bank 2 (Under 8600 GVW without C6P)
|[pic] |
| |
|Click to Enlarge |
Circuit Description
This diagnostic test is designed in order to measure the efficiency of the three-way catalytic converter (TWC) system. Catalytic convertor efficiency is a measure of its ability to store oxygen after converting the levels of hydrocarbon (HC), carbon monoxide (CO), and oxides of nitrogen (NOx) to less harmful gases. The control module is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of the steady cruise speeds used in the past.
Once the conditions for running this diagnostic trouble code (DTC) are met, the control module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The control module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.
For example, if the control module were to command a rich mixture, the upstream heated oxygen sensor (HO2S) voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream oxygen (O2) sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.
Conditions for Running the DTC
• No active secondary AIR DTCs
• No active CMP sensor DTCs
• No active ECT sensor DTCs
• No active EGR DTCs
• No active fuel trim DTCs
• No active IAC DTCs
• No active IAT sensor DTCs
• No active MAF sensor DTCs
• No active MAP sensor DTCs
• No active O2 sensor DTCs
• No active transmission DTCs
• No active EVAP system DTCs
• No active TP sensor DTCs
• No active VS sensor DTCs
• No active misfire DTCs
• The engine speed is 1,000 RPM or more for more than 40 seconds since last idle period
• The engine has been running for at least 360 seconds and the long term fuel trim is stable
• The predicted catalyst temperature is at least 390°C (734°F)
• The system is in closed loop
• The BARO is 73 kPa or more
• The IAT is between -7-117°C (20°-167° F)
• The ECT is between 75-117°C (167-243° F)
• The engine has been idling for less than 120 seconds
• The actual engine speed is within 100 RPM of the desired idle speed
Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold
Action Taken When the DTC Sets
• The control module illuminates the malfunction indicator lamp (MIL) the first time the diagnostic runs and fails.
• The control module will set the DTC and records the operating conditions at the time the diagnostic fails. The control module stores the failure information in the scan tools Freeze Frame/Failure Records.
Conditions for Clearing the MIL or DTC
• The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
• A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
• Use a scan tool in order to clear the DTCs.
Diagnostic Aids
The use of fuel with high sulphur or lead content can degrade a marginal converter's performance. Be sure to check the fuel quality.
An intermittent may be caused by any of the following conditions:
• A poor connection
• Rubbed through wire insulation
• A broken wire inside the insulation
Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.
If a repair is necessary, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the three-way catalytic converter efficiency to appear degraded. Inspect and repair exhaust system as necessary. Refer to Exhaust System Inspection
6. Before the three-way catalytic converter is replaced, make sure that the following conditions are not present:
o Misfire
o High engine oil consumption or coolant consumption
o Retarded spark timing or weak spark
|Step |Action |Value(s) |Yes |No |
|1 |WARNING |-- |Go to Step 2 |Go to Powertrain On |
| | | | |Board Diagnostic |
| |Important: Before clearing the DTCs, use the scan tool Capture Info| | |(OBD) System Check |
| |to save the Freeze Frame and Failure Records for reference. The | | | |
| |control module's data is deleted once the Clear Info function is | | | |
| |used. | | | |
| | | | | |
| |Did you perform the Powertrain On-Board Diagnostic (OBD) System | | | |
| |Check? | | | |
|2 |Are any other DTCs set? |-- |Go to the |Go to Step 3 |
| | | |applicable DTC | |
| | | |table | |
|3 |Check exhaust system for the following: |-- |Go to Step 5 |Go to Step 4 |
| |Leaks | | | |
| |Loose or missing hardware | | | |
| |Repair as necessary. Refer to Exhaust System Inspection in Engine | | | |
| |Exhaust. | | | |
| |Did you find a problem? | | | |
|4 |Verify that the correct original equipment three-way catalytic |-- |Go to Step 5 |Go to Step 6 |
| |converter is installed. | | | |
| |Check the converter for the following: | | | |
| |Dents | | | |
| |Severe discoloration | | | |
| |Holes | | | |
| |Ensure that the oxygen sensors are properly installed and that the | | | |
| |wiring connections are properly retained and not damaged. | | | |
| |Repair as necessary. Refer to Exhaust System Inspection . | | | |
| |Did you find a problem? | | | |
|5 |Using the scan tool, clear the DTCs. |-- |System OK |Go to Step 6 |
| |Start the engine. | | | |
| |Allow the engine to idle until the engine reaches normal operating | | | |
| |temperature. | | | |
| |Select DTC and the Specific DTC function. | | | |
| |Enter the DTC number that was set. | | | |
| |Operate the vehicle, within the Conditions for Setting this DTC, | | | |
| |until the Scan Tool indicates the diagnostic Ran. | | | |
| |Does the Scan tool indicate the diagnostic Passed? | | | |
|6 |NOTE |-- |System OK |-- |
| | | | | |
| |Notice: In order to avoid damaging the replacement three-way | | | |
| |catalytic converter, correct the engine misfire or mechanical fault| | | |
| |before replacing the three-way catalytic converter. | | | |
| | | | | |
| |Replace the catalytic converter. Refer to Catalytic Converter | | | |
| |Replacement in Engine Exhaust. | | | |
| |Is the action complete? | | | |
Bottom of Form
|Trouble Code: P0430 (5.7L V8 VIN R Auto) |Print this code data[pic] |
|Catalyst System Low Efficiency (Bank 2) | |
Number of Trips to Set Code: 1
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• CAT Details
• MIL Details
Trouble Code Conditions:
DTC P0101-P0103, P0106-P0108, P0112-P0118, P0125, P0131, P0132-P0138, P0140, P0141, P0151-P0158, P0160, P0161, P0171-P0175, P0200, P0300, P0325, P0327, P0335, 336, P0341, P0343, P0351-P0358, P0443-P0449, P0502, P0503, P0506, P0507, P1120, P1125, P1133, P1134, P1153, P1154, P1220, P1221, P1275, P1276, P1280-P1286, P1441, P1514-P1518 not set, engine runtime over 6 minutes, ECT sensor over 167ºF, BARO sensor over 72 kPa, IAT sensor over 16ºF, MAF sensor from 15-50 g/sec, Catalyst Temperature over 840ºF, engine running at idle speed for 2 minutes with Actual idle speed within 100-125 rpm of the Desired idle speed, vehicle driven to 22-85 mph, less than a 10% change in engine load, fuel trim stable, and the PCM detected the Catalyst was degraded.
Possible Causes:
• Air leaks at the exhaust manifold or in the exhaust pipes
• Base engine problems (i.e., high engine oil or coolant usage)
• Catalytic converter is damaged, contaminated or has failed
• Continuous engine misfire conditions, or weak or low coil output
• Front HO2S or rear HO2S is contaminated with fuel or moisture
• Rear HO2S is loose in the mounting hole (check it for a leak)
1998 GMC C1500 Suburban - Powertrain - Engine Controls - 5.0L and 5.7L - DTC P0430 Catalyst System Low Efficiency Bank 2 (Over 8600 GVW C6P)1998 GMC C1500 Suburban - Powertrain - Engine Controls - 5.0L and 5.7L - DTC P0430 Catalyst System Low Efficiency Bank 2 (Under 8600 GVW without C6P)
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