Recently my 94 E320 started running rough. I was accelerating quickly and heard a poof sound and that is when the surging and idol hunting started happening. My 20 mpg has ceased and I smell a rich gas exhaust smell. I made the 3 probe engine analyzer and researched all the codes for my M104 6 cylinder HFM/SFI gas engine. Here is what I found in my copy of CS1000, Fault Code Scanner, Mercedes-Benz Instructions, Model Years 1988-98,
Analog/Digital Fault Code Module 1988-98 OB15-11

DM in Ch 1, pin 3 codes 2, 3, 5, 7, 13, 16, & 24

2 Heated oxygen sensor faulty

3 Lambda control faulty - is Lambda control part of the O2 sensor?

5 Exhaust gas recirculation faulty - What is the metal tube called which carries the exhaust gasses for recirculation?

7 Ignition system faulty - Could this be a result of the faulty O2 sensor?

13 Unlisted here

16 Closed throttle position information faulty - Could this be a result of the faulty O2 sensor?

24 Starter ring gear segments and /or crankshaft position sensor faulty - Could this be a result of the faulty O2 sensor?

DM in Ch 8,9,10 pin 3 codes 2, 3, 5, 7, 13, 16, 24

002 Oxygen sensor. No signal (right bank in 120) - What does this mean fault or no signal in right bank in 120?

003 Fuel adaptation (lambda control), inoperative. Engine control module (right bank in 120)

005 EGR exhaust gas recirculation incorrect, fault. Engine control module (right bank in 120)

007 Ignition system defective, fault from Fuel/Ignition control system (right bank in 120)

013 Camshaft position sensor (CMP) signal, fault from Fuel/Ignition control system (right bank in 120)

016 Closed throttle position (CTP) sensor signal incorrect/implausible.

024 Crankshaft position sensor (CKP) signal incorrect or starter ring gear segment damaged.

EA/.CC/ISC pin 14

5 Stop lamp switch (S9/1)

11 Closed throttle recognition signal to engine control module (HFM-SFI)
Fuel safety shut-off to engine control module (HFM-SFI)

HFM/SFI pin 8 codes 4, 5, 9, 13

4 Hot film mass air flow sensor

5 CTP switch

9 O2S 1 (before TWC) - voltage too high, circuit open or voltage implausible

13 O2S (Lambda) control system operating at rich or lean limit

HFM/SFI pin 8 codes 4, 5, 9, 13

004 (006) Intake air temperature sensor, short circuit

005 (007) Intake air temperature sensor, open circuit

009 Not used

013 (015) Throttle valve potentiometer actual value too low

Any suggestions on where I should begin and how I should proceed will be greatly appreciated as I am on a limited income and don't mind doing some dirty work. If anyone knows of some other sources of good used parts please let me know.

I think the first thing I need to do is get the o2 sensor squared away. I have to wait until the first of the month for funds to do this. I also want to clean the exhaust/emission metal tube that runs from right to left across the engine in the back. I can do that job with out any cash so I am looking for some instructions on doing it. I wish I knew what the emissions part is called.

I am still hoping someone out there can advise me how to proceed with repairs. For example where and what to start with first? Any help will be appreciated.

Has your engine wiring harness been replaced?

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".

Clear the codes and start again. Sometimes codes accumulate.

O2 sensor codes can be caused by exhaust leaks, intake manifold vacuum leaks. If your brake issue is a hard peddle, you might have a vacuum leak.

Hello Suginami and 97 SL320,

I will look the wiring harness over carefully and either tape it or replace it as it has not been replaced by me and I bought the car back in 2007.

I will try resetting the codes and see what I come up with afterwards. Do you know how long it takes for the codes to become readable again?

I read somewhere that an easy way to test for (I am not sure which intake or exhaust, probably exhaust?) intake or exhaust leaks is to spray with something (not sure what as I had never heard of the product, I figure it is some kind of penetrating oil like WD-40, I think it is called CIS Spray?) and look for bubbles. Well, I don't always believe everything I read; have either of you ever heard or know of something like that?

I am pretty sure that the caliper is frozen. I will check for vacume leaks and I read about a procedure for a M103 engine. Do you know if it would be a similar procedure for the M104? I figire I need to begin by removing the caliper and take it from there.

Thanks for your input. I look forward to hearing from you again.

Regards,

Henry

Taping up the harness won't help... Most likely since you have so many codes, I would venture a guess that either the engine harness or ETA is no good. Start by clearing them and see which ones come back.

In the meantime it wouldn't hurt to check the condition of the main engine harness and ETA. There should be a white delphi tag around/below the battery tray with a date code. If it was made prior to 1997 most likey the engine harness is no good. Also inspect the engine harness near sensors, where you can see the wire jacket insulation (if its brittle, cracked or missing).

For the ETA you have to cut a slit in the rubber pigtail (from the ETA). Look for the same things: brittle/cracked/missing insulation and corroded wires.



Engine harness is about $1000 and not difficult to install. The ETA can be DIY rewired or sent out to have the pigtail replaced for $200-$500 or reman $900 or new $1500.

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FS: Closing Shop, Bunch of NOS MB parts for sale

I first changed the engine wiring harness and rechecked the codes. I only had three remaining. I replaced the mass air flow sensor and the lambda o2 sensor. That did the trick and it purrs now. The third code was for the brake light sensor which I replaced.

Now I am researching emissions code 5 exhaust gas recirculation faulty. Looking for ideas of what to do next.

Thanks for the update, there are lots of threads on the board that don't have final solutions posted.

I'm not sure how the computer knows that the EGR is working on your car. Some brands have a pressure sensor on the EGR tube, some look at valve position. Some might use the knock sensor and look to see if knock is reduced as the EGR is opened.

I'd put a vacuum gauge on the EGR line and see if it gets a signal. Also check vacuum lines , "switchover valve" ( vacuum solenoid ) , pull the EGR open and look for the idle to fall, maybe remove valve / piping and clean out carbon.

Thanks for the ideas. I will try them. This code 5 has been ongoing and existed prior to all of the repairs I just completed. I was told by the shop I go to (when I can afford it) that it is likely that I need to either change out or clean the egr tube; they said it is possibly due to the faulty design of the egr tube which has been redesigned. So according to them either I remove and clean it out or replace it. I will do your suggestions first.

I also read somewhere that at least one mechanic ran an old speedometer cable or wire through the tube as an easy method of cleaning it out rather than complete removal of the tube. Anyone know of this idea as a possible method of tube cleanout?

BTW, I wanted to post the solutions to my problems with the car as I learn the most from posts that include solutions. I figure that may be of benifit to others as well. I am glad that it is appreciated.

Currently I am attempting to remove the code using the method I have seen posted. I have not been able to remove said code. First, I read the code; Second, within 10 seconds I press the button at number 2 and hold it between 6 and 8 seconds. When I check to see if the code is erased by pressing button number 2 I see that the code is still there. Any ideas about what I need to do differently in order to erase the code? I can't figure out what I am doing wrong and I keep on trying out different ways to accomplish eraseing the code as I need to get the car inspected and likely will not pass the visual check with the check engine light on. My car will not have to pass emissions testing as it is a 1994 and is no longer being checked for emissions.

I have finally been successful at getting the code to clear. Although I am not exactly sure how I did it. I have been doing my testing and clearing procedure with the engine off and the key in the on/run position. I read somewhere that maybe I need to have the vehicle running in order to test/clear the emissions faults. I am guessing that this means that when I connect my homemade reader that the ignition needs to be in the on/run position with the engine not running.

What follows is how I was able to turn the code off. I tried the read/clear procedure with the engine running and it read code 5 and code 5 did not erase after holding the button down for the 6 to 8 seconds. Then I shut the engine off and put the key in the on/run position and I think (?) I attempted to erase the code without first obtaining the reading. This seemed to do something as when I pressed the button down for the 2 to 4 seconds I got absolutly nothing. I was expecting it to blink at least once as it did with my homemade code reader. I checked it a few times and getting the same lack of flashes I looked to see if the check engine light was off. Well it was on; so I turned the key to off and it was still on. I checked for the sensor code and still obtained no blinking LED. I turned the key to off and then back on and noted that the check engine light is now off.

Thus, I am absolutely clueless as to how I successfully cleared the code. Any help understanding this simple process will be greatly appreciated as I am stumped. I actually had the same kind of problems with clearing the codes last time I attempted to clear them and was equally stumped as to what I did to get them to clear. Some cleared easily and I recall at least one of them being a difficult to clear. I just did not bother to post about it at the time as I had more pressing issues to contend with.

I imagine it will likely remain off for at least a few days to a few weeks as this is the usual pattern to my shutting it off before getting an inspection sticker. I have shut it off in the past by disconnecting the battery and leaving it off for awhile. I dislike the battery shut off method as it requires inputting the code for the radio. Which is really no big deal; just a bother.

So, I am really wanting to understand the correct method for reading the codes and if and when the engine needs to be on or off with the key in the on position. I want to know the same information for clearing the codes. As I have said, I have been doing all sensor readings with the key in the on position and the engine off. So, is this the correct procedure for diagnosis both with and without the homemade sensor reader?

Looking forward to my enlightenment on this very simple process.

I'm not sure of the details in clearing the older system.
Jim F is a poster on this site, have a look around his site at k6jrf.com/MB_S500.html

Cleaning the tube with a speedo cable works but finding one these days can be difficult.

I cleaned the tube on my old 124 without removing it. I unbolted both ends, and while I had a speedo cable, it whouldn't make it around the final bend, at the manifold entrance hwere the carbon builds up. You can still poke in there with a small screwdriver or similar pick to clear it out. Your back may need a day or two to recover from being hunched over.

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Prost!

Thanks for the input. I will check out the sight you mention. I will keep my back in mind. I found this you tube about this type of fix. https://www.youtube.com/watch?v=prx9ouhuDuw

After this I have to repack my front wheel bearings.

Replace my electric antenna motor.

Contend with the water on the front passanger floor.

Fix some rust spots.

Reseal the front and back glass.

And I am sure something else fun will come up.

I still can't figure the correct process for removing codes as it dosn't seem to work as the instructions suggest it should. I made and homemade flash diagnostic tool using Arthur's instructions. It cost me about $25.00 as I had to purchase the solder and wire along with everything else. I am so very pleased that it works so well. Except for my befuddlement at code erasure.

94 e320 coupe. runs a little choppy at idle but has decent power. acts like it has a rev limiter at 4000 rpm! any ideas on this?

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