'95 E320 Check Engine Light - PeachParts Mercedes-Benz Forum

johng99 · #1 05-07-2009, 10:05 AM

The (check engine light) CEL on my '95 E320 has come on again - after first round I changed out oxygen sensor and plugs after my Indie evaluated. Now about 50 miles later it is on again. I checked codes (thanks to this site) and am getting codes 4, 5, and 19. This is by reading the led on the car. (I have not yet made the LED code reader, but plan to do so). I have cleared the codes and drove to work this morning (10 miles) with no CEL on.
Car had the wiring harness exchanged in the past.
Any thoughts on what could be happening? Car runs very well, with only an occasional slight hesitation on acceleration from dead stop.
John

deanyel · #2 05-07-2009, 10:33 AM

Strange story - your mechanic read those codes and replaced the O2 sensor? Are you saying you don't know what 4,5 and 19 are?

johng99 · #3 05-07-2009, 10:45 AM

These are the codes that I read last night. My interpretation of the data posted is the following error codes:

4 Air injection system faulty hot film mass air flow sensor with hot wire
5 Exhaust gas recirculation faulty
19 Injectors circuit open or circuit short emission control module adaptation in engine control module at limit

My questions are: is my interpretation correct?
Does anyone have suggestions on next step?

Thanks

John

deanyel · #4 05-07-2009, 11:10 AM

It's the usual routine, clear the codes, drive the car, see what comes back. Also build the code reader, read the codes, clear the codes, see what comes back. 4 may be a bad mass air flow sensor, replace. 5 is likely a blocked EGR pipe, do a search, clean the pipe. I wouldn't worry too much about 19 until you've dealt with the other two.

Arthur Dalton · #5 05-07-2009, 11:18 AM

Classic Combo of codes on 104 HFM for broken vac line from the intake to the SOV valves for EGR and AIR system.

Pull front engine cover and look at the white plastic line going across front of engine to the two piggy-backed vac valves.....if it is cracked /broken, replace with a full rubber line. They all crack from heat fatique.
That is common feed for both SOVs and it will pop 4 and 5 together, along w/19 from the leak.

johng99 · #6 05-07-2009, 01:20 PM

Thanks Arthur - I was hoping you would give some advice. I will check in to this.

Arthur Dalton · #7 05-07-2009, 01:24 PM

That is the first suspect with that code combo. Very common.

If you do find that to be the correct diagnosis, then post back and I will instruct you how to Reset the computer memory for your out of adaptation limit.

The cover I mention is right on top/front of engine..it pulls right off.
Te SOVs and vac line are under that cover.

johng99 · #8 05-10-2009, 08:47 PM

I checked this white plastic line and one end did not seem to be secure. After snugging it up and clearing codes, number 4 and 5 did not reappear. I drove the car for about 75 miles and got the check engine light again.
This time it is only code 19.

What is the procedure for resetting the computer adaptation algorithm and is that most likely my issue now?

Thanks for the help!

John

Arthur Dalton · #9 05-10-2009, 09:00 PM

Don't reset the N3/4 module until you get codes from pin #8.
Post them and then we will set adaptation to Mean.

johng99 · #10 05-11-2009, 10:57 PM

I made the test circuit with the LED and switch from the info. posted here - thanks all. On pin #8 the error codes are: #13 and #20.

How is this used to reset the computer adaptation?

John

( I am learning a lot!)

Arthur Dalton · #11 05-12-2009, 09:25 AM

Good.

Those are high adaptation/trim codes , so a couple of quick checks before you reset memory.

Take the vac line off the fuel pressure Regulator and see if there is any gas in that line. Also, start the car w/hose off and see if fuel comes out that port..if Yes , replace FP reg...... and look at all hoses and clamps for vac leaks. [ vac leaks can be anywhere, so here is a vac routing diagram]

http://www.peachparts.com/shopforum/attachment.php?attachmentid=67045&d=1240263522

If you find a problem w/either of these checks, fix it and then run the car a day or two. If the codes clear themselves , you have found the problem and the ECU has readapted. If not , then manually reset .

To reset memory, take your tool and clear those codes. When all are clear , go back to #8 and you should get a single flash. indicating No codes stored. After the single, wait 2 sec and push your button for 6 secs, turn key off for 10 sec , On for 10 secs , and start car. That gets you to Mean.
Run car and see if codes return.

Note that the reason behind me not wanting you to reset before doing the other checks and possible remedy is so that the ECU can tell you if that was ,in fact , the proper repair..if you had just gone and reset before then, you would never know if you had fixed the problem..we are using the cars abilty to adapt to clue us in if the repair was the culprit. If it does not , then you know you have not fixed it.