update: I got the downstream NOx sensor replaced...and was looking good for a week now.. but then. went to meijers to put in diesel gas... and maybe 10mins later...CEL light is back on... so I have a couple of thoughts? ... it was raining... don't know if that had a contributing factor.. and then i went through a pool of water which i didnt see because it was so dark... so i dont know if the rush of water in the undercarriage did anything? i'm to let the GL dry off for the night. and then i guess a week more... and then go back to the dealer... is the sensor so sensitive? man this truck has been nothing of one worry to the next... and btw last week got a crack in the front windshield...which i just replaced today. blah the story never ends...

 

went to autozone and got a 'P02D3 Cylinder 4 Fuel Injector Offset Learning' ...

20 mins later after I got home ... I turned the GL back on ... no more CEL light... I'm hoping it was the rain? or something got reset on it's own?

 

Not familiar with the GL CEL issues, but in general the CEL should not reset itself. Did the person at AutoZone clear the code for you? Quick search reveals this:

http://repairpal.com/OBD-II-Code-P02...g-at-max-limit

Still a fuel injector issue it appears. I doubt it has anything to do with the rain. The above link shows these as the common causes:

Damaged or contaminated spark plug
Engine sensor failure
Exhaust leak
Fuel injector failure
Powertrain Control Module (PCM) software needs to be updated

You said selling dealer already replaced fuel injector for cyl 1. Now, cyl 4 is acting up. Any chance of them to replace the remaining 5? At the same time all 6 spark plugs?

 

for now they've agreed to change out the fuel injector for cyl 4... im hoping it's the last i see of them.. but i have my doubts.

 

At the same time all 6 spark plugs?[/QUOTE]

Diesels dont have spark plugs.
Jared, Autozone scantools are not capable of properly retrieving the correct problem the cars ecu stores in code. It must be scanned with dealer level diagnostic tool (xentry). Otherwise the selling dealer is just throwing parts at it and hoping you and problems with car finally go away.
The fuel injectors that were replaced for example have to be adapted in and coded for the engines ecu to to operate them correctly. If the selling dealers shop does not have the dealer lever XENTRY setup then they are wasting your time ,their time and money.
Hope this helps

 

Thanks for the correction. I have never owned a diesel car. Good to know after doing a quick read up.

 

thanks #2burners for the info. the mechanic the dealer uses has the xentry system...and now cyl 2 came up as faulty ... so they've replaced 2 and 4... might as well do all of them no? ha.

 

Is there a history of fuel filter service? Has the fuel been tested for water/contaminates ? Gasoline mistakenly put in tank ? If I were the tech these are the first go to's . As fuel injectors are pricey, fuel filtration and quality is key to long injector life. Is the tech aware of coding in the injectors? Make sure if and when they get this resolved a new oem or Mann fuel filter is installed.

 

yah he was thinking biodiesel may have been put in before? what do you mean by coding in the injectors? like configuring the new injector with the computer stuff? i'll ask about the fuel filter as well... thanks again.

 

Yes, injectors have to be configured to car basically . Only can be done with dealer type service tool. Imho, the fuel filter should be changed regardless of when it was put in or if no exact history of replacement considering the multiple injector failures at this mileage. Oem only or Mann filter with latest revision. Fuel test for water and bio content is a must! What part of N.A. Are you located? Bio can be an issue but certain areas dont have it in large percentages.

 

i live in the Chicago area. when I bought the GL i called a Mercedes dealership and asked what gas station can I go to... they said Meijers. none of that biodiesel stuff. luckily theres a Meijers not too far from me. Ill ask about replacing the fuel filter.
Also any other notes or insight you or anyone else may have on keeping the GL in smooth running condition... like i'm getting used to the engine loudness when compared to my minivan or another car...it's much louder and u can really hear the motor running...

and lastly thank u all for you input and time.

 

Change engine and cabin air filters and flush brake fluid. Oil change every 7500 mi. with 229.52 spec oil , fuel filters every 10-20k.
Excessive engine noise is possibly caused by the injectors not being coded in to ecu. If
the mechanic just r+r without doing the proper adaptation and coding, the injector(s) cannot work in harmony with the other injectors. Then the other injectors get told to compensate and thats when all goes awry
Good luck, if it still isnt correct tell the used car dealer you want it serviced by mb.

Hope this helps

 

Ok, so i have made a 2000 mile trip recently and i know place where i have purchased diesel was not where i would normally buy diesel, but try to find a shell in the middle of texas dessert. Anyway.. the car started to shake at idle and cracking more pistachios than usual.. once i got home i pluged in star and came up with Injector 1 and 4 to be replaced. I cleared the code and let it come up again.. this time it was showing only injector 1 but the actual values were still showing 1 and 4 . I addedd some injector cleaner with no success. I was looking at $500 + per injector but then:
SOLUTION:
1. Re-programed the injectors as you would install new ones
2. Cleared all possible values on the pre-teaching screen.
3.GOOD RUNNING DIESEL

i do beleive that this was a fuel related but also a software issue.

Good luck

 

Which programmer are you using and how many miles do you have since you cleared the code?

 

I use xentry, i have over 500miles since i have done this.. no issues

And dont remove the injectors but use the same numbers as they are currently stored on your car, xentry will show them to you, just copy the old numbers and paste them on the new field. i wish i had taken some screenshots.