Nox sensor failure

[Julie1774]

Hey guys, new to this
I see by previous posts that alot of you are having or have had issues with your Nox sensors? My car is a 66 plate c250d coupe with just over 21000 on the clock. My EML came on a few weeks back (2nd time in just over a year) and ive been told its the nox sensor. It was replaced by MB last year when it was in for recall, now theyre telling me ill probably have to pay to have it replaced again.
Is this right or should i seek advice about this? Im normally quite good when dealing with MB but when it comes to the technical stuff im abit lost. Any help would be great.

 

[Ibtasam8]

If it was replaced by MB, should have a 24 month warranty,

 

[Julie1774]

If it was replaced by MB, should have a 24 month warranty,

Thanks for that, I was hoping that would be the case. MB definitely replaced it middle of last year. I have a feeling they will tell me its the other sensor though. Will I have a leg to stand on if it is?

 

[Ibtasam8]

If its the other sensor then I'd imagine you would have to pay.

From what I can tell the NOx sensor seems to be a real issue on MB vehicles. I myself am having issues with mine on a 2015 c200.

 

[Julie1774]

If its the other sensor then I'd imagine you would have to pay.

From what I can tell the NOx sensor seems to be a real issue on MB vehicles. I myself am having issues with mine on a 2015 c200.

Youre right, ive looked into this and MB in Germany have a massive back order on the sensors as theyre unable to keep up with demand in replacing them. IMO I shouldnt be having this issue with a relatively new car with low mileage. Surely MB are accountable for this, as it appears its a worldwide issue with these sensors?

 

[CJD]

My dealer told me they have replaced literally thousands of NOx sensors, and that they will always replace them FOC if the car has a full MB service history - because its a very well known problem.

 

[grober]

There is a difference on warranty provision between items that have replaced FOC under manufacturer warranty and those purhased which have a 2 year warranty? I believe that an item replaced FOC under manufacturer warranty is technically covered only for the remainder of the manufacturer warranty? This is independent of any informal goodwill arrangement which may be in place. This was discussed earlier this year in another NOx thread.
The NOx sensors have gone thro several changes over the years and the latest ones MUST be acccompanied by a software update to make sure they function correctly.

 

[Julie1774]

My dealer told me they have replaced literally thousands of NOx sensors, and that they will always replace them FOC if the car has a full MB service history - because its a very well known problem.

My car has been serviced by an independant MB specialist who uses all of the MB software and genuine parts. He the biggest MB specialist in the area. Will this cause an issue?

 

[CJD]

My car has been serviced by an independant MB specialist who uses all of the MB software and genuine parts. He the biggest MB specialist in the area. Will this cause an issue?

Of that i'm not sure, you can only ask the question to the indy who did the work - they may do them as a good will gesture, but thats down to them i'm afraid.

 

[Julie1774]

Of that i'm not sure, you can only ask the question to the indy who did the work - they may do them as a good will gesture, but thats down to them i'm afraid.

Ok thanks for your input, time will tell I suppose.

 

[Deleted member 65149]

My car has been serviced by an independant MB specialist who uses all of the MB software and genuine parts. He the biggest MB specialist in the area. Will this cause an issue?

Unfortunately I fear that MB won’t be interested if all the services haven’t been carried out by them.

A few months ago I had both sensors replaced on my 2012 30,000 mile C350, with MB contributing £1,000 towards the cost, leaving me to pay just £200. My MB dealer who I bought the car from new and had every service done by them, initially said that there would be no financial help. But I contacted MB UK directly and they agreed to help with the £1k.

If you don’t ask them they definitely won’t help. In your circumstances they may still refuse to help, but it has to be worth a try because those sensors are very expensive.

Good luck

 

[Julie1774]

Unfortunately I fear that MB won’t be interested if all the services haven’t been carried out by them.

A few months ago I had both sensors replaced on my 2012 30,000 mile C350, with MB contributing £1,000 towards the cost, leaving me to pay just £200. My MB dealer who I bought the car from new and had every service done by them, initially said that there would be no financial help. But I contacted MB UK directly and they agreed to help with the £1k.

If you don’t ask them they definitely won’t help. In your circumstances they may still refuse to help, but it has to be worth a try because those sensors are very expensive.

Good luck

Thanks for that, its much appreciated. If MB know theres a global issue with these sensors then I really cant understand why the affected models are being recalled to have them rectified. My 1st service was at MB and the 2nd and 3rd at the specialist. Ive also been told thay using an independant wont affect my statutory rights?

 

[Bobclive2]

Unfortunately this is one more problem associated with diesel powered light vehicles, once on the second hand market when servicing gets lax the cars will become so costly to repair they will become almost worthless, this will then have a financial knock on effect on far newer models. This is the reason my 3 cars are petrol, including my Merc.

 

[rf065]

My 1st service was at MB and the 2nd and 3rd at the specialist. Ive also been told thay using an independant wont affect my statutory rights?

It doesn't, and apart from that, the nox sensor is not something that gets serviced anyway. What I mean by that is that nothing is done to it during a service that would prevent it from breaking down later, even if Mercedes had carried out all the services, so they cannot blame your independant for the fault occuring.
Fact is though, your warranty has expired and the previous sensor replaced under warranty, was only covered under the original 3 year warranty. You would need to ask Mercedes if they will repair it under "goodwill", but by going to an independant they may just refuse.

 

[grober]

Thanks for that, its much appreciated. If MB know theres a global issue with these sensors then I really cant understand why the affected models are being recalled to have them rectified. My 1st service was at MB and the 2nd and 3rd at the specialist. Ive also been told thay using an independant wont affect my statutory rights?

When exactly was your car registered 66 plate would be SEPT 2016 onwards possibly meaning your 3 year MB manufacturer warranty has expired- meaning you are now in Goodwill territory?

 

[Deleted member 65149]

Unfortunately this is one more problem associated with diesel powered light vehicles, once on the second hand market when servicing gets lax the cars will become so costly to repair they will become almost worthless, this will then have a financial knock on effect on far newer models. This is the reason my 3 cars are petrol, including my Merc.

As much as I oppose diesel powered vehicles, and never having owned one in over 50 years of motoring, I have to say that this issue isn’t unique to the oil burnets. My car is fuelled by petrol and I still had the same problem. The NOx sensors fitted as original equipment were clearly not up to the job, a failing for which MB should take full responsibility.