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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 28830
Experience:  Over 15 years experience as a Mercedes dealer technician
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I own a G350 bluetec 2011 - 54 000km. Recurring problem of

Customer Question

I own a G350 bluetec 2011 - 54 000km. Recurring problem of adBlue warning light coming on with full adBlue tank. Have replaced sensors and 6x reset. Any suggestions?
Submitted: 1 year ago.
Category: Mercedes
Expert:  Pete replied 1 year ago.

Hi my name is ***** ***** I will be happy to help with this today.I need a little more info to assist better.

Has your vehicle had the recall done for the software update at all by a Mercedes dealer?

Let me know so we can continue,thanks Pete.

Customer: replied 1 year ago.
Don't know. Had a recall for sump replacement.
Expert:  Pete replied 1 year ago.

O.k.,there is an issue with the heating element operation for the tank itself and there is updated software for the Selective Catalytic Reduction control unit SCR on almost all of these models with the 642 engine code U42.The recall number I see is(###) ###-####If this was not checked and done this should be done as this corrects false warnings for the ad blue system.This recall is covered in cost by Mercedes.

If this is checked and found out to be o.k. I have seen the SCR with an internal electrical fault that will cause false warnings like this as well as wiring damage leading from the sensors at the tank.I would then have the wiring checked to make sure this is o.k. and if found o.k. I suspect the SCR may need replaced and programmed.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.Thanks Pete.

Customer: replied 1 year ago.
Pete. Thanks. I will have the car checked out soon. Regards. Stephan
Expert:  Pete replied 1 year ago.

Your welcome.Let me know if you need anything else and feel free to rate my help here.

Thanks Pete

Customer: replied 1 year ago.
Pete,Mercedes Benz has replaced the NOX filters. Seems to be ok for the moment. I have picked up using Google that replacing NOX filters is not the root of the problem but rather that carbon buildup is. What is your opinion on this and how do I prevent this from happening. In South Africal 50pp Diesel is the norm. We don't have 10pp readily available. Would this make any difference?RegardsStephan
Customer: replied 1 year ago.
should rather read 50 ppm
Customer: replied 1 year ago.
Will any sort of additive cure this problem or just make it worse?