JustAnswer
P0171
|Trouble Code: P0171 (3.8L V6 VIN 1 Auto) |Print this code data[pic] |
|Fuel Trim System Lean (Bank 1) | |
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• Fuel Details
• MIL Details
Trouble Code Conditions:
DTC P0101-P0103, P0107, P0108, P0121-P0123, P0130-P0138, P0140, P0141, P0201-P0206, P0300, P0401-P0405, P0410, P0440-P0446, P0506, P0507, P1404 or P1441 not set, engine started, vehicle driven at less than 82 mph at 550-4000 rpm, BARO sensor over 70 kPa (10.1 psi), ECT sensor from 68-230ºF, IAT sensor from 64-158ºF, MAF sensor from 2.8-150 gm/s, MAP sensor from 16-105 kPa (2.6-15.2 psi), fuel level over 10%, and the PCM detected the Long Term fuel trim value was more than +20% for 6 seconds. The PCM controls the air/fuel metering system to good overall fuel economy, driveability, and emission control. During open loop, the PCM determines fuel delivery based on sensor signals, without the oxygen sensor input. During closed loop, the PCM adds oxygen sensor inputs to calculate Short and Long term fuel trim fuel delivery adjustments. Short Term fuel trim values change rapidly in response to changes in the oxygen sensor signals. Long Term fuel trim makes coarse adjustments in order to maintain an air/fuel ratio of 14.7:1.
Possible Causes:
• Air leaks in intake manifold, exhaust pipes or exhaust manifold
• Fuel control sensor is out of calibration (ECT, IAT or MAF)
• Low fuel pressure (fuel filter clogged, pressure regulator failure)
• One or more injectors restricted or pressure regulator has failed
• HO2S element is contaminated, deteriorated or has failed
• Vacuum hose is disconnected, broken, leaking or loose
2000 Pontiac Bonneville - Powertrain - Engine Controls - 3.8L - DTC P0171 Fuel Trim System Lean
Top of Form
[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.8L > DTC P0171 Fuel Trim System Lean
DTC P0171 Fuel Trim System Lean
|NOTE |
|Applicable vehicles: |
|Bonneville (VIN H) |
DTC P0171 Fuel Trim System Lean
|Table 1: |Fuel Trim Cells |
|Table 2: |DTC P0171 - Fuel Trim System Lean |
Circuit Description
To provide the best possible combination of driveability, fuel economy, and emissions control, a closed loop air/fuel metering system is used. While in closed loop, the PCM monitors the HO2S 1 signals and adjusts the fuel delivery based upon the HO2S signal voltages. A change made to the fuel delivery will be indicated by the long term and short term FT values, which can be monitored with a scan tool. Ideal fuel trim values are around 0 percent. If the HO2S signals are indicating a lean condition the PCM will add fuel, resulting in fuel trim values of more than 0 percent . If a rich condition is detected, the fuel trim values will be less than 0 percent , indicating that the PCM is reducing the amount of fuel delivered. If an excessively lean condition is detected on bank 1, the PCM will set DTC P0171. The PCMs maximum authority to control long term fuel trim allows a range between -20 percent and +20 percent . The PCMs maximum authority to control short term fuel trim allows a range between -20 percent and +20 percent . The PCM monitors fuel trim under various operating conditions (fuel trim cells) before determining the status of the fuel trim diagnostic. The fuel trim cells are as follows:
Fuel Trim Cells
|Cell |Purge ON |Purge OFF |
|Idle (Cell 0) |X |-- |
|Decel (Cell 1) |-- |-- |
|Normal (Cell 2) |X |X |
|Accel (Cell 3) |X |X |
|High Flow (Cell 4) |X |-- |
|L.T. Fuel Trim average more than +17 percent |
|S.T. Fuel Trim more than +2 percent |
The vehicle may have to be operated in all of the above conditions before the PCM determines fuel trim status. The amount of fuel trim deviates from 0 percent in each cell and the amount that each cell is used directly affects whether or not the vehicle must be operated in all of the cells described above to complete the diagnostic.
Conditions for Running the DTC
• None of the following active DTCs are present:
o Throttle position (TP) sensor
o Evaporative emissions (EVAP) system
o Misfire
o Intake air temperature (IAT) sensor
o Manifold absolute pressure (MAP) sensor
o Fuel injector circuit
o EGR pintle position
o Engine coolant temperature (ECT) sensor
o Crankshaft position (CKP) sensor
o Mass air flow (MAF) sensor
o Vehicle speed sensor (VSS)
o Camshaft position (CMP) sensor
o Heated oxygen sensor (HO2S)
o Electronic spark timing (EST)
• The engine coolant temperature is between 20°C (68°F) and 110°C (230°F).
• The intake air temperature is between -18°C (0°F) and 70°C (158°F).
• The manifold absolute pressure is between 15 kPa and 85 kPa.
• The throttle angle is steady and less than 90 percent .
• The vehicle speed is less than 132 km/h (82 mph).
• The engine speed is between 600 and 4000 RPM.
• The BARO is more than 70 kPa.
• The mass air flow is between 3 gm/s and 150 gm/s.
Conditions for Setting the DTC
• The long term fuel trim is at or near the maximum authority of +20 percent .
• The short term fuel trim is at or near the maximum authority of +20 percent .
• All of the conditions described above have been met in the Fuel Trim Cells.
Action Taken When the DTC Sets
• The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
• The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.
Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
• The DTC can be cleared by using a scan tool.
Diagnostic Aids
Check for the following conditions:
• The HO2S pigtail may be routed incorrectly and contacting the exhaust system.
• Ensure that the PCM to engine block grounds are clean, tight, and in the proper locations. Refer to IGN Switch and PCM Feeds in Engine Controls Schematics.
• The fuel system will go lean if the fuel pressure is too low. The PCM can compensate for some decrease. However, if the fuel pressure is too low, a DTC P0171 may be set. Refer to Fuel System Pressure Test (VIN K) or to Fuel System Pressure Test (VIN 1) .
• The fuel injectors, refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) or Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) .
• Check for the following vacuum leak conditions:
o Any disconnected or damaged vacuum hoses, refer to Emission Hose Routing Diagram .
o An incorrectly installed or malfunctioning crankcase ventilation valve, refer to Crankcase Ventilation System Inspection .
o Any vacuum leaks at the throttle body, the EGR valve, and the intake manifold mounting surfaces
• Check for exhaust leaks that may cause a false lean condition to be indicated. An exhaust leak may cause outside air to be pulled into the exhaust gas stream past the HO2S, causing the system to appear lean. Refer to Exhaust Leakage - Not OBD II in Engine Exhaust.
• Disconnect the MAF sensor and see if the lean condition is corrected. If so, replace MAF sensor. Refer to Mass Airflow Sensor Replacement .
• Fuel contamination--Water, even in small amounts, can be delivered to the fuel injectors. The water can cause a lean exhaust to be indicated. Excessive alcohol in the fuel can also cause this condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
• A faulty connection at the PCM--Inspect the harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, and faulty terminal to wire connection. Use a corresponding mating terminal to test for proper terminal tension.
• Inspect the wiring harness for damage. If the harness appears to be OK, observe the HO2S 1 display on the scan tool while moving connectors and wiring harnesses related to the engine harness. A change in the display will indicate the location of the malfunction.
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. DTCs other than P0171 may indicate that a condition is present which may cause a lean condition. If this is the case, repairing the condition which caused the other DTC will most likely correct DTC P0171.
4. If DTC P0171 test passes while the Failure Records conditions are being duplicated, the lean condition is intermittent. Refer to Diagnostic Aids for additional information on diagnosing intermittent conditions.
DTC P0171 - Fuel Trim System Lean
|Step |Action |Values |Yes |No |
|1 |Was the Powertrain On-Board Diagnostic (OBD) System Check |-- |Go to Step 2 |Go to Powertrain On |
| |performed? | | |Board Diagnostic |
| | | | |(OBD) System Check |
|2 |Are any DTCs other than P0171 set ? |-- |Diagnose applicable |Go to Step 3 |
| | | |DTCs, Go to | |
| | | |Diagnostic Trouble | |
| | | |Code (DTC) List/Type | |
|3 |Start and run the vehicle in closed loop. |+15 percent|Go to Step 5 |Go to Step 4 |
| |Observe long term FT and the short term FT displayed on the scan | | | |
| |tool. | | | |
| |Are the values more than the specified value? | | | |
|4 |Review and record the scan tool Failure Records data. |-- |Go to Step 5 |Go to Diagnostic Aids|
| |Clear DTC P0171 and operate the vehicle to duplicate the Failure | | | |
| |Records conditions. | | | |
| |Monitor the scan tool Specific DTC info for DTC P0171 while | | | |
| |operating the vehicle to duplicate the Failure Records conditions.| | | |
| |Continue operating the vehicle until the DTC P0171 test runs and | | | |
| |note the test result. | | | |
| |Does the scan tool indicate DTC P0171 failed this ignition? | | | |
|5 |Visually and physically inspect the vacuum hoses for splits, |-- |Go to Step 23 |Go to Step 6 |
| |kinks, and improper connections. Refer to Emission Hose Routing | | | |
| |Diagram . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|6 |Visually and physically inspect the crankcase ventilation valve |-- |Go to Step 23 |Go to Step 7 |
| |for proper installation. Refer to Crankcase Ventilation System | | | |
| |Inspection . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|7 |Inspect the throttle body inlet screen for damage or for the |-- |Go to Step 23 |Go to Step 8 |
| |presence of foreign objects which may alter the airflow sample | | | |
| |through the MAF sensor. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Refer to Throttle Body Air Inlet Screen Replacement . | | | |
| |Was a problem found? | | | |
|8 |Start the engine and note the idle quality. |-- |Go to Step 9 |Go to Step 11 |
| |Is the idle high or unsteady? | | | |
|9 |With the engine idling, observe the Idle Air Control display on |5 |Go to Step 11 |Go to Step 10 |
| |the scan tool. | | | |
| |Is the value more than the specified value? (Value is displayed in| | | |
| |counts). | | | |
|10 |Visually and physically inspect the throttle body, the intake |-- |Go to Step 23 |Go to Step 11 |
| |manifold, the EGR valve and the EGR feed pipes for vacuum leaks. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|11 |Check the idle air control system operation. Refer to the Idle Air|-- |Go to Step 23 |Go to Step 12 |
| |Control (IAC) System Diagnosis . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|12 |Check the fuel for excessive water, alcohol, or other |-- |Go to Step 23 |Go to Step 13 |
| |contaminants. Refer to Alcohol/Contaminants-in-Fuel Diagnosis . | | | |
| |Was a problem found? | | | |
|13 |Visually and physically inspect the injector grounds, the PCM |-- |Go to Step 23 |Go to Step 14 |
| |power and grounds, and the sensor grounds to verify that the | | | |
| |circuits are clean, tight, and in the proper locations. Refer to | | | |
| |Ground Distribution Schematics in Wiring Systems. | | | |
| |If a problem is found, repair as necessary. Refer to Wiring | | | |
| |Repairs in Wiring Systems. | | | |
| |Was a problem found? | | | |
|14 |Perform the Evaporative Emissions Control (EVAP) System Check. |-- |Go to Step 23 |Go to Step 15 |
| |Refer to Evaporative Emission Control System Diagnosis . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was problem found? | | | |
|15 |Perform the Fuel System Pressure Test. Refer to Fuel System |-- |Go to Step 23 |Go to Step 16 |
| |Pressure Test (VIN K) or Fuel System Pressure Test (VIN 1) . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was problem found? | | | |
|16 |Visually and physically inspect the following components for |-- |Go to Step 23 |Go to Step 17 |
| |vacuum leaks: | | | |
| |The intake manifold | | | |
| |The injector O-rings | | | |
| |The EGR adapter | | | |
| |The EGR valve | | | |
| |The EGR feed pipes | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|17 |Visually and physically inspect the exhaust manifold for leaks and|-- |Go to Step 23 |Go to Step 18 |
| |loose or missing hardware. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|18 |Disconnect the MAF sensor electrical connector. |0 percent |Go to Step 21 |Go to Step 19 |
| |Operate the vehicle in closed loop while monitoring the Short Term| | | |
| |FT displayed on the scan tool. | | | |
| |Does Short Term FT decrease to approximately the specified value? | | | |
|19 |Check the fuel injector operation. Refer to Fuel Injector Solenoid|-- |Go to Step 23 |Go to Step 20 |
| |Coil Test - Engine Coolant Temperature Between 10-35 Degrees C | | | |
| |(50-95 Degrees F) or Fuel Injector Solenoid Coil Test - Engine | | | |
| |Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F) . | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|20 |Visually and physically inspect the HO2S to ensure that the sensor|-- |Go to Step 23 |Go to Diagnostic Aids|
| |is installed securely and that the HO2S pigtail and wiring harness| | | |
| |are not contacting the exhaust or otherwise damaged. | | | |
| |If a problem is found, repair as necessary. Refer to Heated Oxygen| | | |
| |Sensor Wiring Repairs in Wiring Systems. | | | |
| |Was a problem found? | | | |
|21 |Inspect the MAF sensor screen for foreign objects, debris, or |-- |Go to Step 22 |Go to Step 23 |
| |damage. | | | |
| |Was a problem found? | | | |
|22 |Replace the MAF sensor. Refer to Mass Airflow Sensor Replacement .|-- |Go to Step 23 |-- |
| |Is the action complete? | | | |
|23 |Review and record the scan tool Failure Records data. |-- |Go to Step 2 |System OK |
| |Clear DTC P0171. | | | |
| |Operate the vehicle to duplicate the Failure Records conditions. | | | |
| |Monitor the scan tool Specific DTC info for DTC P0171 while | | | |
| |operating the vehicle to duplicate the Failure Records conditions.| | | |
| |Continue operating the vehicle until DTC P0171 test runs and note | | | |
| |the test result. | | | |
| |Does the scan tool indicate DTC P0171 failed this ignition? | | | |
Information for Code p0171
Code p0171 means that the computer has noticed (by reading the oxygen sensors) that there is too much air going into bank one (the bank that includes cylinder number one in the firing order in v style engines). This information is also applicable to code p0174 as this code is the same except of the opposite bank of cylinders.
Engine control computers need to have a specific ratio of air to fuel in order to work properly, and if there is too much of one or the other then it will set a code.
There are several very common things that cause this code:
Dirty Mass Airflow Sensor
Vacuum Leak
Bad Oxygen Sensor(s)
Running Out of Gas
Some other things that can cause this code:
Clogged Fuel Injectors
Leaking Exhaust System
Evaporative Emissions System Malfunction
EGR System Malfuncion
The first thing that I would do is make sure no one has ran out of gas in the vehicle recently. This will cause this code almost every time. The next thing is to clean the MAF sensor. You can buy cleaner specifically for this procedure.
Then you should check for vacuum leaks, especially ones that are after the MAF like tears in the tube that goes from the airbox to the engine. If this is torn it will let air in that the computer cannot tell is coming into the engine.
The next most common cause is bad Oxygen sensors. If they are not working properly then they will not be reading the amount of oxygen in the exhaust gas.
P0300
|Trouble Code: P0300 (3.8L V6 VIN 1 Auto) |Print this code data[pic] |
|Multiple Engine Misfire Detected | |
OBD II Monitor Type: CCM Details
Indicators: MIL Details
• MISFIRE Details
• MIL Details
Trouble Code Conditions:
DTC P0101, P0102, P0103, P0107, P0108, P0116-P0118, P0121-P0123, P0125, P0336, P0341, P0502-P0503, P1106-P1107, P1114, P1115, P1121, P1122, P1336, 1351, P1361, P1362 and P1374 not set, engine speed from 525-6600 rpm, ECT sensor at 21-255ºF, TP angle steady, system voltage over 10.0v and the PCM detected a crankshaft speed variation in 2 or more cylinders characteristic of a misfire. If the misfire is severe, the MIL will flash on/off on 1st trip!
Possible Causes:
• Base engine mechanical fault that affects one or more cylinders
• Fuel metering fault (high fuel pressure or fuel contaminated)
• EVAP system problem or the EVAP canister is fuel saturated
• EGR valve is stuck open or the PCV system has a vacuum leak
• Ignition system fault (a coil) that affects more than one cylinder
• MAF sensor contamination (it can cause a very lean condition)
• TSB 99-06-04-005B contains a repair procedure for this code
• TSB 03-06-04-030 contains a repair procedure for this code
2000 Pontiac Bonneville - Powertrain - Engine Controls - 3.8L - DTC P0300 Engine Misfire Detected
Top of Form
[pic]
[pic][pic]PATH: Diagnostics > Diagnostic Routines > Powertrain > Engine Controls - 3.8L > DTC P0300 Engine Misfire Detected
DTC P0300 Engine Misfire Detected
|NOTE |
|Applicable vehicles: |
|Bonneville (VIN H) |
DTC P0300 Engine Misfire Detected
Circuit Description
The powertrain control module (PCM) has the ability to detect a misfire by monitoring the 3X reference and camshaft position input signals from the ignition control module. The PCM monitors crankshaft speed variations (reference period differences) to determine if a misfire is occurring. If 2 percent or more of all cylinder firing events are misfires, emission levels may exceed mandated standards. The PCM determines misfire level based on the number of misfire events monitored during a 200 engine revolution test sample. The PCM continuously tracks 16 consecutive 200 revolution test samples. If 11 or more misfires are detected during any 10 of the 16 samples, DTC P0300 will set. If the misfire is large enough to cause possible 3-way catalytic converter damage, DTC P0300 may set during the first 200 revolution sample in which the misfire was detected. In the case of a catalyst damaging misfire, the MIL will flash to alert the vehicle operator of the potential of catalyst damage.
Conditions for Running the DTC
• None of the following DTCs are set:
o Vehicle speed sensor (VSS)
o Throttle position (TP) sensor
o Engine coolant temperature (ECT) sensor
o Crankshaft position (CKP) sensor
o Camshaft position (CMP) sensor
o Manifold absolute pressure (MAP) sensor
o Mass air flow (MAF) sensor
• The engine speed is between 550 and 5800 RPM.
• The system voltage is between 9 and 18 volts.
• The ECT indicates an engine temperature between -6°C (20°F) and 120°C (248°F).
Conditions for Setting the DTC
The PCM is detecting a crankshaft RPM variation indicating a misfire sufficient to cause 3-way catalytic converter damage or emissions levels to exceed mandated standards.
Action Taken When the DTC Sets
• The PCM will illuminate the MIL during the second consecutive trip in which the diagnostic has been run and failed unless three way converter damage is possible in which case the light will illuminate after the first failure.
• If equipped with traction control, the PCM will command the EBTCM via the serial data circuit to turn OFF traction control, and the EBTCM will illuminate the TRACTION OFF lamp.
• The PCM will store conditions which were present when the DTC set as Freeze Frame and Failure Records data.
Conditions for Clearing the MIL/DTC
• The PCM will turn OFF the malfunction indicator lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
• The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
• The DTC can be cleared by using a scan tool.
Diagnostic Aids
The scan tool provides information that can be useful in identifying the misfiring cylinder. If the DTC P0300 is currently stored as DTC status Failed Since Code Clear, the misfire history counters (Misfire History Cyl #1-#6) will still contain a value that represents the level of misfire detected on each cylinder. The scan tool displayed misfire counter values (Misfire History Cyl. #1 through #6) can be useful in determining whether the misfire affects a single cylinder, a cylinder pair (cylinders that share an ignition coil - 1/4, 2/5, 3/6), or is random. If the largest amount of activity is isolated to a cylinder pair, check for the following conditions:
A misfire DTC may set if components that affect the crankshaft position sensor have been recently replaced, and the Crankshaft Position System Variation Learn has not been performed. If the diagnostic table does not identify a problem then perform the Crankshaft Position System Variation Learn.
If the misfire is random, check for the following conditions:
• Crankshaft Position System Variation
• Refer to Crankshaft Position System Variation Learn.
• The crankshaft position system variation compensating values are stored in the PCM non-volatile memory after a learn procedure has been performed. If the actual crankshaft position variation does not match the crankshaft position system variation compensating values stored in the PCM, DTC P0300 may set. The crankshaft position system variation learn procedure is required when any of the following service procedures have been performed:
o The PCM has been replaced.
o DTC P1336 has set.
o The engine has been replaced.
o The crankshaft has been replaced.
o The harmonic balancer has been replaced.
o The crankshaft position sensor has been replaced.
o Any engine repairs which disturb the crankshaft/harmonic balancer to crankshaft position sensor relationship.
• Check the secondary wires associated with the affected cylinder pair for disconnected ignition wires or for excessive resistance.
• If any spark plug wire resistance is more than the specified value, replace the affected spark plug wires.
VIN 1 Spark Plug Wires Resistance
3280-4921 ohms per meter (1000-1500 ohms per foot)
VIN K Spark Plug Wires Resistance
3280-4921 ohms per meter (1000-1500 ohms per foot)
• A damaged or malfunctioning ignition coil. Check for cracks, carbon tracking, or other damage. Also check the coil secondary resistance. The secondary resistance should be within the specified range.
Ignition Coils Secondary Resistance
5000-8000 ohms.
• Switch ignition coils and retest. If the misfire follows the coil, replace the ignition coil.
• Check the system grounds. Ensure all the connections are clean and properly tightened.
• A mass air flow (MAF) sensor output that causes the PCM to sense a lower than normal air flow will cause a lean condition. Try operating the vehicle within the Failure Records conditions. If the lean or misfiring condition is not present with the MAF sensor disconnected, replace the MAF sensor.
• If the PCM stops receiving data from the EBCM/EBTCM, DTC P0300 can set due to a loss of rough road data. Check for stored ABS/TCS DTCs, especially DTCs related to a serial data malfunction. Refer to Diagnostic System Check - ABS in Antilock Brake System .
• Vacuum leaks that cause intake air to bypass the MAF sensor will cause a lean condition. Check for disconnected or damaged vacuum hoses, an incorrectly installed or malfunctioning crankcase ventilation valve, or for vacuum leaks at the throttle body, the EGR valve, and the intake manifold mounting surfaces.
• Perform a fuel system pressure test. A malfunctioning fuel pump, plugged fuel filter, or malfunctioning fuel system pressure regulator will contribute to a lean condition. Refer to Fuel System Pressure Test (VIN K)or to Fuel System Pressure Test (VIN 1)
• Check the fuel injectors. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) or to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F)
• Check for contaminated fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis.
• Check the EGR system for a leaking valve, adapter, or feed pipes which will contribute to a lean condition or excessive EGR flow.
• Excessive open loop operation caused by extended idling or short trip driving may leave deposits on the heated oxygen sensors. The deposits cause oxygen sensors to respond slowly to exhaust oxygen content, affecting fuel control and causing a misfire to be indicated at idle. This condition is not permanent. To determine if this condition is causing the DTC P0300 to be set, review the freeze frame and fail records data for DTC P0300. If the DTC P0300 occurs at high engine speeds, the condition described above did not cause the DTC P0300 to set. If the DTC P0300 occurs at idle or very low engine speeds and at engine coolant temperatures less than 80°C (176°F), the condition described above is very likely the cause of the DTC P0300 being set. The deposits on the heated oxygen sensors can be eliminated by operating the vehicle fully warm at mass air flows above 15 gm/s.
|WARNING |
|Important:: If the level of misfire was sufficient to cause possible catalyst damage (if the MIL was flashing), ensure that the DTC|
|P0420 test is completed and passed after verifying the misfire repair. |
Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Test Description
The numbers below refer the step numbers on the diagnostic table.
2. A malfunctioning injector circuit, crankshaft position system variation not learned condition, or incorrect rough road data from the EBCM/EBTCM may cause a misfire DTC to be set. If any of the indicated DTCs are set with DTC P0300, diagnose and repair the other DTC before using the DTC P0300 table.
3. The Misfire Current Cyl # display may normally display a small amount of activity (0-10 counts) but should not steadily increment during an entire 200 revolution test sample period.
4. Depending upon the cause of the misfire, the Misfire History Cyl # counter will display a very large number for the misfiring cylinders. Values for the non-misfiring cylinders will be less than half as much as the misfiring cylinders. When investigating a misfire, always start with items associated with the cylinder that has the largest number of counts stored in the Misfire History Cyl # counter.
5. If the misfiring cylinders are companion cylinders, the condition is most likely linked to the ignition system.
9. Check for faulty terminal connection, grooves, corrosion, pitting, loose fit.
17. Check for the following conditions that may contribute to the engine misfire: the engine oil pressure, a damaged accessory drive belt or pulley, a damaged driven accessory (generator, water pump, drive belt tensioner, etc.), a loose or broken motor mount.
DTC P0300 - Engine Misfire Detected
|Step |Action |Values |Yes |No |
|1 |Was the Powertrain On-Board Diagnostic (OBD) System Check performed?|-- |Go to Step 2 |Go to Powertrain On|
| | | | |Board Diagnostic |
| | | | |(OBD) System Check |
|2 |Are any other DTCs set? |-- |Go to Diagnostic |Go to Step 3 |
| | | |Trouble Code (DTC) | |
| | | |List/Type | |
|3 |Start and idle the engine. |-- |Go to Step 5 |Go to Step 4 |
| |Review and record the scan tool Freeze Frame data. | | | |
| |Operate the vehicle to duplicate the conditions present when the DTC| | | |
| |was set (as defined by the Freeze Frame data). | | | |
| |Monitor the scan tool Misfire Current Cyl # display for each | | | |
| |cylinder. | | | |
| |Is the Misfire Current # display incrementing for any cylinder, | | | |
| |indicating a misfire currently occurring? | | | |
|4 |View the Misfire History Cyl # display on the scan tool. |-- |Go to Step 5 |Go to Step 8 |
| |Does Misfire History Cyl # display a very large value for more than | | | |
| |one cylinder? | | | |
|5 |Are the misfire values displayed on the Misfire History Cyl # |-- |Go to Step 9 |Go to Step 6 |
| |related to companion cylinders (i.e. 1/4, 2/5, 3/6)? | | | |
|6 |Perform a visual inspection of the following areas: |-- |Go to Step 22 |Go to Step 7 |
| |The vacuum hoses for improper connections and damage. Refer to the | | | |
| |Emission Hose Routing Diagram . | | | |
| |The spark plug wire connections at the coils and at the spark plugs.| | | |
| |The engine and PCM grounds. Ensure that the connections are in the | | | |
| |proper locations, clean, and tight. Refer to Ground Distribution | | | |
| |Schematics in Wiring Systems . | | | |
| |The EGR to intake manifold piping for proper connections and signs | | | |
| |of damage. | | | |
| |Visually and physically inspect the PCV valve for improper | | | |
| |installation and damaged O-rings. Refer to Crankcase Ventilation | | | |
| |System Inspection. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|7 |Check the fuel pressure. |333-376 kPa |Go to Step 8 |Go to Fuel System |
| |Is the fuel pressure within the specified range? |(48-55 psi) | |Pressure Test (VIN |
| | | | |K) or to Fuel |
| | | | |System Pressure |
| | | | |Test (VIN 1) |
|8 |Check for proper fuel injector operation. Refer to Fuel Injector |-- |Go to Step 22 |Go to Step 9 |
| |Solenoid Coil Test - Engine Coolant Temperature Between 10-35 | | | |
| |Degrees C (50-95 Degrees F) or to Fuel Injector Solenoid Coil Test -| | | |
| |Engine Coolant Temperature Outside 10-35 Degrees C (50-95 Degrees F)| | | |
| |. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|9 |Important: : If carbon tracking is apparent at either end of the |-- |Go to Step 22 |Go to Step 10 |
| |spark plug wires, replace the affected ignition wire and the | | | |
| |associated ignition coil or spark plug. | | | |
| |Visually inspect the ignition wires and coils associated with the | | | |
| |misfiring cylinders for the following conditions: | | | |
| |Any carbon tracking/arching and damage | | | |
| |Connection to the incorrect cylinders at the coil and spark plug | | | |
| |Faulty terminal connections at the coil and spark plug | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|10 |Install a J 26792 spark tester at the spark plug end of the ignition|-- |Go to Step 15 |Go to Step 11 |
| |wire associated with the misfiring cylinders. | | | |
| |Jumper the spark plug end of the companion cylinder ignition wire to| | | |
| |engine ground. The companion cylinder is the cylinder that shares | | | |
| |the same ignition coil (i.e. 1/4, 2/5, 3/6). | | | |
| |Crank the engine while observing the spark tester. | | | |
| |Is spark present? | | | |
|11 |Measure the resistance of the ignition wires associated with the |3280-4921 |Go to Step 22 |Go to Step 12 |
| |cylinders that were indicated as misfiring. |ohms per | | |
| |Replace the ignition wires if the resistance measures more than the |meter | | |
| |specified range. |(1000-1500 | | |
| |Was a problem found? |ohms per | | |
| | |foot) | | |
|12 |Measure the resistance of the secondary ignition coils associated |5,000-8,000 |Go to Step 22 |Go to Step 13 |
| |with the misfiring cylinders. |? | | |
| |If the resistance is not within the specified range, replace the | | | |
| |malfunctioning ignition coils. Refer to Ignition Coil Replacement . | | | |
| |Was a problem found? | | | |
|13 |Remove the ignition coils associated with the misfiring cylinders. |-- |Go to Step 22 |Go to Step 14 |
| |Inspect the coils for signs of carbon tracking, cracks, or other | | | |
| |damage. | | | |
| |If a problem is found, replace the affected coils. Refer to Ignition| | | |
| |Coil Replacement . | | | |
| |Was a problem found? | | | |
|14 |Important: : Be sure to reinstall the fuel injector fuse. |-- |Go to Step 20 |Go to Step 21 |
| |Leave the ignition coils disconnected. | | | |
| |Connect a test lamp across the ignition module primary circuit | | | |
| |terminals. | | | |
| |Remove the fuel injector fuse. | | | |
| |Observe the test lamp while cranking the engine. | | | |
| |Does the test lamp blink? | | | |
|15 |Remove the spark plugs from the cylinders associated with the |-- |Go to Base Engine |Go to Step 16 |
| |misfire. Refer to Spark Plug Replacementin Engine Electrical. | |Misfire Diagnosisin| |
| |Visually inspect the spark plug electrodes for excessive fouling. | |Engine Mechanical. | |
| |Was a problem found? | | | |
|16 |Important: : If carbon tracking is apparent on any of the spark |-- |Go to Step 22 |Go to Step 17 |
| |plugs, replace the affected spark plugs and the associated ignition | | | |
| |wires. | | | |
| |Visually inspect the spark plugs for the following conditions: | | | |
| |Carbon tracking, cracks, or other damage to the insulator | | | |
| |Electrode damage or incorrect gap | | | |
| |If a problem is found, replace the affected spark plugs. | | | |
| |Was a problem found? | | | |
|17 |Reinstall the spark plug. |-- |Go to Step 22 |Go to Step 18 |
| |Check for engine mechanical problems. Refer to Base Engine Misfire | | | |
| |Diagnosis in Engine Mechanical. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|18 |If the condition occurs while driving, check for transaxle TCC |-- |Go to Step 22 |Go to Step 19 |
| |problems. Refer to Torque Converter Diagnosis in Automatic Transaxle| | | |
| |4T65-E. | | | |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|19 |Check for contaminants in the fuel. Refer to |-- |Go to Step 22 |Go to Diagnostic |
| |Alcohol/Contaminants-in-Fuel Diagnosis . | | |Aids |
| |If a problem is found, repair as necessary. | | | |
| |Was a problem found? | | | |
|20 |Replace the ignition coils associated with the misfiring cylinders. |-- |Go to Step 22 |-- |
| |Refer to Ignition Coil Replacement . | | | |
| |Did you complete the repair? | | | |
|21 |Replace the ignition control module. Refer to Ignition Control |-- |Go to Step 22 |-- |
| |Module Replacement. | | | |
| |Did you complete the repair? | | | |
|22 |Review and record the Freeze Frame data. |-- |Go to Step 2 |System OK |
| |Clear the DTCs. | | | |
| |Start and idle the engine. | | | |
| |Operate the vehicle to duplicate the conditions present when the DTC| | | |
| |was set as defined by the Freeze Frame data. | | | |
| |Monitor the scan tool Misfire Current Cyl # display for each | | | |
| |cylinder. | | | |
| |Is the Misfire Current Cyl # display incrementing for any cylinder | | | |
| |indicating a misfire currently occurring? | | | |
Bottom of Form
Code p0300 is a code that is generated when your engine has a misfire that is not related to only one cylinder. Sometimes this code will be set in addition to other codes such as p0301 which means that there is a misfire on cylinder 1 (cylinder 1 is the number one cylinder when looking at the firing order. It is generally the forward most cylinder on the engine.). If these engine codes are present as well the you should diagnose those first as they are probably causing code 0300.
This code will set your check engine light and needs to be fixed as soon as possible. If it is not then you will probably need to replace your catalytic converter as well as the problem that is causing your misfire.
There are many causes for this obd code. Since it is a "random misfire" or "multiple misfire" this means that the misfire is on different cylinders and not just one all the time. This means that the most likely causes are things like:
Low Fuel Pressure
Vacuum Leak
EGR system malfunction
Internal Engine Problems (such as low compression)
BUT other things that can cause this code are:
Faulty Coil
Faulty Spark Plugs and/or Wires
Camshaft or Crankshaft sensors
Ignition module
Computer
The first thing I would do if the problem wasn't obvious by inspection is a full tune up. Many times this will fix this code. If you want to do more diagnosis so you don't just throw parts at it you will need to check each of the above items starting with the top four.
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.