Diagnostic Trouble Code #19 Repair Eprom for V8 Mercedes-Benz



Diagnostic Trouble Code #19 Repair Eprom for V8 Mercedes-Benz

This is one of the Diagnostic Trouble Codes (DTC) that occurs in the Diag Module (Menu#6) which states: Fuel injectors open/short or self-adaptation in LH-SFI control module (N3/1) at limit. This code lights the Check Engine Lamp (CEL) because it directly affects engine emissions. It's not a 'nice' code as you will see!

The DTC_19 problem can happen in any fuel system. When it occurs, it means you have reached the limit of electronic adaptation correction. This problem originally started in hot humid climates and it caused the air/fuel mixture to get richer with great regularity. When the partial adaptation number reaches 0.85, the limit is reached and the CEL cames on!

So just erase and forget it. Sorry, this DTC is different from other codes. When you reset it, it will come back within a few miles of driving b/c the self-adaptation (S/A) is at the limit value. When you reset this code, you are just resetting the CEL light in the Diagnostic Module (Menu#6) but you can't change the S/A value itself. If you think you can get the car to pass a smog test, you are mistaken.

1990 thru 1994 W124s and W140s had only +/-15% correction built into the fuel computer's firmware. MBs solution is to sell you new firmware encased in new hardware at the cost of over $3000! The firmware resides in an eprom that can be easily replaced. A number of companies have issued updated firmware by replacing the eproms. Some examples are BMW, Volvo and GM.

When dealing with this issue, the amount of correction is one consideration, but solving the deviation is another. If the mix has gone rich due to pressure changes or vacuum leaks, then fixing that is the correct solution. Many times it is due to a cracked/broken vacuum line, so that should be your first check point.

If nothing abnormal is found and if the car runs great, has no vacuum leaks, fuel pressure is within spec but still the CE lights showing DTC_19 meaning that the fuel computer is running "rich" and if it still has closed loop control of Lambda then updated firmware (new eprom) will solve the problem. New firmware allows that old limit of 0.85 to be increased to 0.68. In oher words, the limits have been increased to +/-32%. MB found that the system will still have closed loop control, thus the new limits.

The 119 LH cars seem to settle out with its long-term correction at or around 0.82. When this occurred in my '94 S500, it stayed at 0.82. It's now over 5+ years since the eprom was replaced, it's running fine and passing CA smog tests with no problem. After two years with the new eprom, the S/A was 0.85. I decided to replace the MAF and O2 sensor since those are the two main sensors that determine S/A. Today, the S/A is 0.93 with the new eprom, MAF and O2 sensor.

The new eprom has fixed every instance of the problem, about 40+ MBs! It's a very cost effective way to permanently solve this problem. It can't be ignored if you live in a SMOG state since even if the car's emissions are within limits (and many times they are!), it will not be allowed to pass since the fuel computer has an "emissions fault".

The replacement eprom comes with a detailed installation instructions including the TSB info on the problem. You can replace the present eprom with a newly programmed unit with the new firmware as described above. The picture shows a closeup of the replacement eprom with the fuel computer open. It's a simple task to open the computer and replace the eprom. The instructions cover all details of this task.

Price is $69 plus $6 s/h. Please click on the icon to send me email.

Eprom Fitment Chart

Chassis

Year

Model

Engine

Remarks

124.034

94-95

E420

119.975 LH

DI = Distributor Ignition

124.034

90-93

400E

119.975 LH

 

124.036

90-93

E500

119.974 LH

500E 93

129.067

94-95

SL500

119.972 LH

 

140.043

94-95

S420

119.971 LH

 

140.042

7/91-

400SE

119.971 LH

420SEL, 400SEL 92-93

140.051

94-95

S500

119.970 LH

500SEL 92-93

140.070

94-95

S500 Cpe

119.970 LH

500SEC 92-93

All MBs have LH-SFI w/ DI

To order one or more for your car, click here [pic]to send an Email containing;

- your full name and address including city, state and zip,

- a phone number where I may contact you if needed,

- your Email address,

- Mercedes MODEL and YEAR info,

- PayPal payment preferred. Will take cashiers checks and USPS Money Orders, no foreign MO!

DTC_19 Eprom is copyright© 2000-2010 by K6JRF, Jim Forgione and JRF Engineering.

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