The check engine light is lit on my 94 E420. I recently had the wiring harness replaced.

My mechanic seems to be having a bit of problems determining what the cause of the light is. He says the code that remains is pretty generic. He has taken 2 seperate readings (clearing light and codes in between). Here is what I'm told:

- Fault Codes Indicated:
DM CIRCUIT
19) Fuel Injector Circuit, Fault from fuel control system.

One thing that he noticed was that the engine was not reaching operating temperature, so he replaced the thermostat. He then reset the Engine control module stating "Possible adaptation out of range". Since then the light has come back on.

The car runs great and the gas cap is on tight.

Does anyone have any ideas as to what else we can check?

Thanks!

Willy
94 E420

There is a service bulletin on this subject!! The computer is running at the RICH limit. Repair is NEW computer!!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Can you elaborate?

Does the service bulliten refer to this specific fault code? Do you have a copy I can see?

What does a new computer cost?

Willy

"What does a new computer cost?"

Big bucks! Rebuilts are probably available from Beckman in N. Carolina.

The bulletin is interesting as it has different recommendations for cars in the Jacksonville zone. It does refer to DM code 19 specifically, but in the zones outside Jax it says to verify long term fuel trim with scanner (lower than .92). It also says to test for other reasons first before replacing the controller. The text of the bullentin is talking about cars in warrantee and the reasons for long term fuel trim adaption at limit increase due to other causes as the vehicle ages.

Email me if your would like the bulletin.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Lovely! Hopefully I won't need a new one.

Just in case, do you have contact info on Beckman in N. Carolina?

I assume that you would not recommend getting one from a salvage yard, right? I checked one of the online salvage yard search engines. These computers are available from $200 to $500. They also mention 2 different kinds for my vehicle:

124 Type, ECU, E420, thru #B993871 and
124 Type, ECU, E420, from #B993872

How would I check? Where is the computer located anyway?

I would love to get a copy of the bulletin. What methods can you use for delivery?

Thanks!

Willy

Steve,

Thanks for the Service Bulletin. I owe you one!

I'll pass this off to my mechanic, but I'm preparing for the worst... him telling me I need a new LH-SFI control module.

Willy

You must use the modified version listed on the service bulletin, otherwise the engine will still run too rich!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Interesting, as the car "seems" to be running ok.

One question though... is this a common problem with these computers? Do all 94 E420s run with their check light on? Have you replaced many of these?

The Service Bulletin I'm looking at is REF No.: MBNA 07.4/2 and it refers to these vehicles in the Jacksonville Region and then all other regions? Is this the one?

BTW... the original module part# is 016 545 13 32. The new one referred to in this TSB is 021 545 70 32.

Thanks!

I have replaced a handfull of these computers for this. The problem usually only happened in the warm (hot) climate.

There is no real ill effect that I am aware of other than the light being on and increased emmissions and power.

I think if run.exe could crack the e-prom code, we could reprogram the old chip to work right for 10.00 dollars.

Anyway, that is a fantasy I think.

Good luck with the repair.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Well, the car was recently purchased from Houston.. and the problem seemed to begin down there.

So, my choices are to buy a new one (around $1800... no way!), or buy a used one from a salvage yard ($200 - $500) and hope it solves the problem. Unfortunately, via salvage, I will probably only be able to find the original computer, and not the replacement version that MB recommends.

A third alternative (just a thought anyway) would be to send my computer in for a chip upgrade at (let say) http://www.jetchip.com. It would cost me about $325 with a one day turnaround. Hopefully they will check out the entire computer to make sure it is up to spec. Heck.. .it would be nice if I could get a salvage one cheap and then send that one in! Hmm... I'll have to pursue this one a bit further. Has anyone dealt with these guys?


[Edited by wjm on 03-22-2001 at 10:20 PM]

Willy,
please find as a join document all the story for my 94 E220 Coupe.
First of all an injector was changed and the same behavior occurred
It start from the wiring harness which was corroded by the acid of the battery !!! After having the cable replaced my
mechanic tell me that the ECU (Engine Control Unit) is out of order.
My car is in a MD garage in south of France (Near Marseille/Toulon) and now stuck for 3 weeks.
So I wrote to MD Customer Service, in Paris, but the answer is: your car is too old and has 150 000 kilometers, so we
cannot do anything for you !
The new reference of the Bosch ECU was given by Mercedes and the Bosch references were given by the Bosch Shop .

I have order the ECU to MD yesterday and I will bring back the old one and will try to have it repaired; But by who ???

Mercedes Ref on the ECU : 015 545 9532
New Mercedes ref is : 016 545 5532

Bosch Ref on the ECU : 0261 200 442
New Bosch Ref are : 0261 203 231 and 0261 203 230

But about your problem I would like to know why the wiring harness was CHANGED ?
I wonder if you have changed the gasoline filter and checked that the injection pressure is correct. I have been told
that before starting any investigation on the ECU, they start from this checking: This is very important.

Thanks for all and waiting for answer about the cable replacement.

Willy,
I have also to tell you that the new ECU for my car will cost about 7800 FF (1100 Dollards/bucks)

Willy,

I was curious about JET, so I sent an email which said:

I have a '94 S500 Cpe and am interested in your 'chip'. Per your advertisement (below), you state 22-24 hp increase AND the use of 89 octane fuel. As you know, MB recommends 91 octane fuel.

Are you saying that one can change to "mid-grade" octane fuel after the chip mod???

Here's the answer I received (quoted verbatim):

"No, just if you are running regular you would need to upgrade the fuel to 89 octane or better so you will be fine."

Now what kind of HS is this, "...if you are running regular"? What S500 runs on regular?

Makes me very suspicious, doesn't it you?

__________________
Regards . . . . JimF
-------------------
'94 S500 Cpe

Visit my Mercedes Web Page

Since I was able to find a computer which was the exact same version as the one I had in my car for a relatively cheap price, I though I would go that route first.

I snapped the old one out and put the new one in and then went to my mechanic to have all of the computers cleared/reset.

It seems to have solved my problem (at least temporarily). Normally the check engine light would come in the following day (with light driving). It's been off for 4 days now.

Should I have the same problem in the future, I'll replace it with a newer software revision as suggested by Mercedes Benz. Heck, I'll keep my eyes out for this newer computer to see if I can get one just as cheap.

Willy

Steve- could you send me the MB Bulletin on replacing the engine computer due to a rich fuel trim?

Thanks,

:-) neil

PS: could you check out my post on fuel trim, OBDII procedures, and CHECK ENGINE light? I'm getting readings for short term fuel trim of 271%.