'94 E500 Code 19 (019) Check Engine ON.

[Daveb12]

Greetings,

My tech is telling me the issue with my check engine light is Code 19. He said all post 1992 V8's have an issue with the Fuel Control Module and 'back in the day' the factory would 're-flash' the unit.

Now he said you need to get a new (or eBay) unit.

The car does rough idle when cold, but other than that it is mainly the ANNOYING bright red check engine light that is the issue.

Anyone with code 19 experience and/or with the Fuel Control Module?

Thanks,

Dave

 

[Klink]

Greetings,

My tech is telling me the issue with my check engine light is Code 19. He said all post 1992 V8's have an issue with the Fuel Control Module and 'back in the day' the factory would 're-flash' the unit.

Now he said you need to get a new (or eBay) unit.

The car does rough idle when cold, but other than that it is mainly the ANNOYING bright red check engine light that is the issue.

Anyone with code 19 experience and/or with the Fuel Control Module?

Thanks,

Dave

Code 19 is caused when the "anticipatory" fuel mixture, that is to say, the calculated fuel mixture before it is subjected to correction via the oxygen sensor / "lambda" feedback loop is either too rich or too lean relative to the corrected mixture. More simply, the corrective part of the system has to correct the mixture too much. How much correction is "too much" is determined by some very tight parameters that were set by the SAE, the California Air Resources Board, etc. etc. The fuel injection system is actually capable of working efficiently and effectively at correction values far greater than those permitted by those parameters. If those parameters are exceeded, a message is sent to the DM / "diagnostic module" and it generates the fault code and lights the "check engine" light.

In almost all cases, this code is caused by vacuum leaks, a leaking fuel pressure regulator diaphragm, or much more rarely, by a deviating air mass sensor. Obviously, these faults may also exist in combination.

There is a small bit of truth to what your technician is thinking, but it only applies to certain specific 4.2L models with California emissions equipment, and even if you had one of those, there are inexpensive workarounds for that very specific problem.

Due to time constraints, I will not be able to comment on this topic for a number of days, but I did want to stop you from feeling that you had to get a new control unit, at least not yet, and especially not if your engine is running well and not emitting any exhaust smoke, etc. You are extremely unlikely to need a different control unit unless your car is fitted with an incorrect control unit.

 

[gsxr]

Everything Klink said: ^^^

First check would be the fuel pressure regulator and vacuum hose, and then every other vac hose/pipe under the hood.

For TRUE diagnosis, you need a digital scanner to read the exact adaptation values. You need to know if the mixture is too lean, or too rich. That will help pinpoint the root cause. I'd say your chances of needing a new LH module are very similar to your chances of being struck by lightning.

 

[highway41]

As my CEL is back on, it got me looking for an answer to an age old question I have every time the CEL comes on. Reading your quote:

"Code 19 is caused when the "anticipatory" fuel mixture, that is to say, the calculated fuel mixture before it is subjected to correction via the oxygen sensor / "lambda" feedback loop is either too rich or too lean relative to the corrected mixture. More simply, the corrective part of the system has to correct the mixture too much. How much correction is "too much" is determined by some very tight parameters that were set by the SAE, the California Air Resources Board, etc. etc. The fuel injection system is actually capable of working efficiently and effectively at correction values far greater than those permitted by those parameters. If those parameters are exceeded, a message is sent to the DM / "diagnostic module" and it generates the fault code and lights the "check engine" light."​

Does this mean that even though the CEL has indicated a fault, the engine is still correcting the fuel/air mixture to the desired 14.7:1 rate? Reason I ask is that the car always seems to run better when the CEL comes on; like it defaults to a richer mixture.

 

[Klink]

As my CEL is back on, it got me looking for an answer to an age old question I have every time the CEL comes on. Reading your quote:

"Code 19 is caused when the "anticipatory" fuel mixture, that is to say, the calculated fuel mixture before it is subjected to correction via the oxygen sensor / "lambda" feedback loop is either too rich or too lean relative to the corrected mixture. More simply, the corrective part of the system has to correct the mixture too much. How much correction is "too much" is determined by some very tight parameters that were set by the SAE, the California Air Resources Board, etc. etc. The fuel injection system is actually capable of working efficiently and effectively at correction values far greater than those permitted by those parameters. If those parameters are exceeded, a message is sent to the DM / "diagnostic module" and it generates the fault code and lights the "check engine" light."​

Does this mean that even though the CEL has indicated a fault, the engine is still correcting the fuel/air mixture to the desired 14.7:1 rate? Reason I ask is that the car always seems to run better when the CEL comes on; like it defaults to a richer mixture.

Actually, that is possible. If it is a dramatic difference between how it feels with the light on, vs. the light off, then something is definitely malfunctioning in a bad way. If you have access to one, a dealer level scanner should enable you to see the amount of the mixture correction applied, and it's direction towards either rich or lean. There are probably numerous other methods to figure this out, but having been a dealership or importer employee for the last thousand years, I have been spoiled by always having access to a dealer level scanner.

 

[highway41]

Actually, that is possible. If it is a dramatic difference between how it feels with the light on, vs. the light off, then something is definitely malfunctioning in a bad way. If you have access to one, a dealer level scanner should enable you to see the amount of the mixture correction applied, and it's direction towards either rich or lean. There are probably numerous other methods to figure this out, but having been a dealership or importer employee for the last thousand years, I have been spoiled by always having access to a dealer level scanner.

When it's only the CEL, I usually wait until a couple other things break/happen before taking it to Brumos where it is well known. Only need one more thing now as the antenna mast has stopped working but I rarely listen to the radio anyway. Will let you know the diagnosis once done. Thanks. Bill