Hi, first post. I need some help. I purchased a 2010 GL350 Bluetec diesel about a year ago as a hauler for the grandchildren. Purchased largely using the funds we got from VW on the buyback for our diesel Jetta Sportswagon. Quite an upgrade for us!! I am a committed DYI guy (see my website www.newhillgarage.com) but the following facts have me stumped.

The vehicle has roughly 55,000 miles. Last digits on the VIN are 594817. Last fall, I received a check engine light. I purchased an iCarsoft code reader (based on the advice of this site), which allowed me to diagnose and repair a faulty pressure sensor in the DPF. I gave myself a pat on the back over that one.

Last December I got another check engine light. The code was 203D17 "Fill sensor Adblue has a short circuit to positive" and also P203D "Reductant level sensor circuit high". I did a lot of web searches but come up empty on previous history that would lead me to a fix. I reset it a few times and it would come right back in a few miles. Decided to ignore it for a while and see what happened.

In July, I checked the codes. Strangely, the original codes had cleared but now I was showing a new code: 20BE1B "The output for heating element Adblue tank has a malfunction". So a new code but still involving the SCR unit.

At some point in there, I pulled the tool kit and exposed the control unit for the SCR. I inspected all the wiring I could see, expecting maybe insulation degradation or mice damage. None found. I did pull the multiplug from the control unit and cleaned it thoroughly with contact cleaner. The 20BE1B code came right back.

A few months ago the battery expired. I put in a new battery from Mercedes. I reset quite a few codes due to low voltages and reset the SCR codes too. I thought I had a fix when the SCR codes didn't reappear after a long test drive. But about 2 days later I got a check engine light. Still showing as 20BE1B.

Around this time I dropped the plastic cover on the SCR unit under the vehicle (well, partially dropped it as it looks like you need to remove the exhaust to get it completely off) and found a round connector that is relatively exposed to road conditions. Thought this might be a culprit so I cleaned it thoroughly with contact cleaner. Am still getting the 20BE1B code

So that's it, in great detail. I'm looking for advice, free or otherwise. I am not inclined to engage the dealership as I suspect that $4000 later they will replace the entire SCR Adblue unit which may or may not fix the problem.

Are there any known areas of the harness that I should inspect?
Are there any ground points that I can clean?
Any and all advice is appreciated!!!

 

 

Thanks. Will do some reading over at w211.