NOX SENSOR

[aliley61]

I have a 2015 220e CDi BLUETEC - Last November (2020)the engine light came on, took it Mercedes dealership in Newcastle upon Tyne. Just to find the fault they wanted nearly £200 inc VAT. Once they detected the fault they said it was a Nox sensor and the final bill for fault finding and fixing was £870. I thought at the time since the car had done just over 30 k miles, this fault shouldn't have occurred especially as my average annual mileage is about 6k. Mercedes told me that they would contact the manufacturers HQ to see if they would replace free of charge as a goodwill gesture given its low mileage. The response was negative so we had to go ahead and pay the full amount. Now coincidentally almost 12 months to the day, the engine light has come on again and Mercedes have told me I have to book it in again pay the diagnostic fee, they will check, there are two sensors, if it is the sensor that they replaced, they will do the work free of charge as it is under warranty but if it is the other sensor I will have to pay again. Since last year I have hardly done 4000 miles, I am finding this situation strange that a Mercedes car, this age, this mileage would have these problems. Does anyone have any knowledge or experience of what would happen to the car if I don't go ahead with this. TIA

 

[Blobcat]

Hello and welcome,

I've moved your thread into the technical section as "Meet Ups and Events" isn't really the best place for it...

With regard to NOX sensors and Engine Warning Lights it is unfortunately very common - please have a search on the forum as there are many threads on the subject. Some owners have had Mercedes do the work under warranty and others have had more of your experience with some very significant bills...

It's not just a Mercedes issue, most modern diesels are failing with the emissions equipment unfortunately.

 

[onefortheroad]

Theres 2 nox sensors , 1 before and 1 after the dpf, the 2 communicate with each other and adjust fueling and ad blue spraying AFAIK. They are meant to be replaced in matching pairs.

2015 was the year of the garbage sensors unfortunately, I think were now onto version 5 since then.

Buy a cheap obd2 scanner , don't keep giving £170 to mb for scans .

 

[LostKiwi]

As mentioned there are a number of iterations of these things. If they replace them they need replacing in pairs and they need a corresponding software update. I'd push MB very hard to get this done FOC.

 

[mattkh]

....... Mercedes told me that they would contact the manufacturers HQ to see if they would replace free of charge

Did they tell you who manufactures the NOx sensor, I would love to know.

 

[aliley61]

I have never been told that they should have been done in pairs, and last year I took my car to a local garage that I use for MOT and they did a diagnostic check which revealed NOX sensor fault but when I took that to MB they said they would have to run their own check and wouldn't replace the sensor without their own diagnostic check, I have spoken to MB Head Office (think it was in Holland) and they refused to agree the repair free of charge. I guess I will try again with my local MB dealer but not very hopeful !!

 

[Botus]

Recall

Received recall letter today and looking into the experiences of others and recommendations I do not wish to get this done. However, as this recall now sits on the DVSA record would this mean car would fail next MOT. I asked this question at a mercedes specialist a couple weeks ago and he said...

forums.mercedesclub.org.uk

Recall - software update performed, EML on when collected

MB dealers get serious knuckel wraps from MB UK when there is a complaint. Your dealer will change sharpish. Keep it polite with the dealer. Let him dig his own grave.

forums.mercedesclub.org.uk