MercC350Coupe2011
Active Member
Hello everyone. As the title says, I have got NOx sensors problem for over a year since the day I bought my car!
My car is a Mercedes C350 2011 coupe with the M276 engine. It is V6 petrol and it has two banks (that means it has two NOx sensors). Let me give you some background to understand the full story. Just to point out that I am an automotive engineer but I am not working on engines and MB but on suspensions for other OEMs. I am mentionening that to highlight that I am not someone who doesn't know anything about cars. I am a car guy fixing many problems myself.
Since the day I bought my car and after only driving 30-40 miles on my way back home I got an engine light. I connected my diagnostic tool and I saw a problem in bank 1 NOx sensor. I decided to continue my journey because I couldn't return the car for many reasons that it's not worth going through all of them now. I found a brand new genuine NOx sensor on ebay in a very good price. It was fitted by an independent garage( who probably just cleared the codes but didn't connect to a star tool) and the dealer had paid for the fix so I was a happy new owner of a Mercedes.
However after driving a few days, I got an engine light back again. I put my diagnostic tool and I saw a problem with the NOx sensor at bank 2 this time. I decided to search for a second hand sensor on ebay to avoid paying the 500 pounds to Mercedes. I found a cheap used one and the sensor was fitted by the same independent garage I did the first one. I believe again he just cleared the codes and he didn't do an SCN coding since he is not a MB specialist. In fact I am almost sure they don't even know if it's needed coding or not.
Unfortunately after driving a few days the engine light came back. I assumed that the sensor from ebay wasn't good. So I bought another one from ebay a little bit more expensive this time. Even though it was advertised as a genuine continental sensor when I got it I realised that the box wasn't genuine Mercedes and had the part number correct but it was saying that it was for brake pads. The sticker was just paper and not plastic as in the original sensors I had. Anyway, because I was fed up with this situation I booked a car ramp and I changed the sensor myself. I don't have a star tool just a MB icarsoft diagnostic tool. So I just cleared the codes and I thought I had solve the problem.
However again after driving a few miles the engine light came back on. Even though some people here had said that the petrol engine doesn't need SCN coding I was thinknig that probably it needs because a MB specialist had told me to go to Mercedes because they couldn't do it. So finally yesterday I went to MB of Coventry and after describing the situation they told me they will update the ECU because it needs to know. However I think they only informed the ECU for the bank 2 sensor not the bank 1 if that makes any difference.
I have a few questions and I would appreciate if someone who knows can help me out.
- Do the PETROL engines need SCN coding/update ECU or I just change the sensor and clear the codes and I am good to go?
- If the engine ECU needs update/SCN coding how it is possible that the sensor in bank 1 doesn't give a problem and it is only the sensor at bank 2? I would have expected to have taken an error at bank 1 when I had changed the first sensor initially.
- Any suggestions what might be the issue?
- What would you propose to do next since I am totally lost and don't know what to decide next?
This problem together with a steering vibration has been going on for over a year and I am so frustrated that I am thinking to sell it and buy another car. I hope I will be able to solve it because it is a good car otherwise.
My car is a Mercedes C350 2011 coupe with the M276 engine. It is V6 petrol and it has two banks (that means it has two NOx sensors). Let me give you some background to understand the full story. Just to point out that I am an automotive engineer but I am not working on engines and MB but on suspensions for other OEMs. I am mentionening that to highlight that I am not someone who doesn't know anything about cars. I am a car guy fixing many problems myself.
Since the day I bought my car and after only driving 30-40 miles on my way back home I got an engine light. I connected my diagnostic tool and I saw a problem in bank 1 NOx sensor. I decided to continue my journey because I couldn't return the car for many reasons that it's not worth going through all of them now. I found a brand new genuine NOx sensor on ebay in a very good price. It was fitted by an independent garage( who probably just cleared the codes but didn't connect to a star tool) and the dealer had paid for the fix so I was a happy new owner of a Mercedes.
However after driving a few days, I got an engine light back again. I put my diagnostic tool and I saw a problem with the NOx sensor at bank 2 this time. I decided to search for a second hand sensor on ebay to avoid paying the 500 pounds to Mercedes. I found a cheap used one and the sensor was fitted by the same independent garage I did the first one. I believe again he just cleared the codes and he didn't do an SCN coding since he is not a MB specialist. In fact I am almost sure they don't even know if it's needed coding or not.
Unfortunately after driving a few days the engine light came back. I assumed that the sensor from ebay wasn't good. So I bought another one from ebay a little bit more expensive this time. Even though it was advertised as a genuine continental sensor when I got it I realised that the box wasn't genuine Mercedes and had the part number correct but it was saying that it was for brake pads. The sticker was just paper and not plastic as in the original sensors I had. Anyway, because I was fed up with this situation I booked a car ramp and I changed the sensor myself. I don't have a star tool just a MB icarsoft diagnostic tool. So I just cleared the codes and I thought I had solve the problem.
However again after driving a few miles the engine light came back on. Even though some people here had said that the petrol engine doesn't need SCN coding I was thinknig that probably it needs because a MB specialist had told me to go to Mercedes because they couldn't do it. So finally yesterday I went to MB of Coventry and after describing the situation they told me they will update the ECU because it needs to know. However I think they only informed the ECU for the bank 2 sensor not the bank 1 if that makes any difference.
I have a few questions and I would appreciate if someone who knows can help me out.
- Do the PETROL engines need SCN coding/update ECU or I just change the sensor and clear the codes and I am good to go?
- If the engine ECU needs update/SCN coding how it is possible that the sensor in bank 1 doesn't give a problem and it is only the sensor at bank 2? I would have expected to have taken an error at bank 1 when I had changed the first sensor initially.
- Any suggestions what might be the issue?
- What would you propose to do next since I am totally lost and don't know what to decide next?
This problem together with a steering vibration has been going on for over a year and I am so frustrated that I am thinking to sell it and buy another car. I hope I will be able to solve it because it is a good car otherwise.
