NOx - Understanding How Many Of Us

[Fenman666]

Hi everyone,

Thought I'd add to the list. My car is a 2015 E220 which I bought used from a dealer. Had the "refill AdBlue" message come up with the EML.

Filled up and still, the EML light stayed on which indicated an issue with the NOx sensor.

Checked the MB website and the car is due the diesel software update. Will this fix the issue most likely or do the actual NOx sensors need replacing? Don't fancy getting ripped off by the main dealers

 

[Fenman666]

I have the same car and after taking it in for the update as soon as I left the dealer the eml light came on.
I purchased a nox sensor from fleabay £124 so thought was worth a go fitted it (15mins) cleared all codes and all is still good

 

[MoCLK]

Thanks, good to know. Will take a look on eBay just incase.

 

[scotland1]

I'll add to the list. I have a 2016 E350 AMG Night Edition estate. I had the EML come on at 31000 miles with a NOX sensor code. I cleared the code & all was well for a long time. Around 35000 the EML was back on with the same DTC so cleared it again but the interval for the EML coming on started to get more frequent. I the got the AdBlu message xxx miles until engine start not possible. Put it into the stealership for investigation; downstream NOX sensor failure. £850 later all back to normal but haven't driven very far since so time will tell. Wish I'd tried an aftermarket part but I would have needed it coded. Had discussion with stealership about these premature failures to see if MB would contribute to cost but he told me they said 'NO'. I have since e-mailed customer services at MB & Gary Savage @ Daimler and am awaiting a reply. Thes NOX sensor & AdBlu problems seem to be widespread & MB I'm sure are well aware of this. Perhaps if enough people inform DVSA it might force MB to do something?? Will let you all know what reply I receive.

 

[DITTRICH]

My Nox sensor on my s205 started throwing up faults at 176k miles. I replaced the entire unit. I kept the old unit and will buy a replacement bosch lambda sensor and keep it as a spare, or sell it. The whole mercedes unit £384 A0009056204. Bosch lambda sensor £80 ish. I think I got my money's worth. Also, the petrol Nox sensor did not require coding to the vehicle like diesels, where there are 2 sensors and a heating element (as it was explained to me).

 

[MoCLK]

Does this 100% need to go to Mercedes or can an independent with Star diagnostic fix it? I also heard it can be coded out.

I have a relative in London with an E-class diesel estate under warranty, that has been waiting 2 weeks for the sensor and MB have no idea of when they will arrive/be produced!

I have 60 more miles left to drive mine lol and I'm saving it incase!

 

[PeteS]

I had the adblue warning and booked the car into my local dealer. They looked at the car for the day and told me that it needed parts and the parts were on back order and the parts could be 3 to 4 months. I asked what would happen if the counter got to zero and was told that it would not start. I was not happy about this and the fact that the parts were in back order. A week later I was at 40 miles left and I spoke to the dealer who told me to call in with Mercedes Assist and then bring the car in. They would have a car for me to use whilst mine was waiting to be repaired. When I got there the service manager explained that he did not have a car available but would arrange hire one for me. Mercedes Assist gave me a lift home. I had an interesting chat on the way home and was told that there was a way of over riding the warning message. Within the week Mercedes had released the parts 2 Nox sensors and my car was repaired. I guess Mercedes were unhappy about having to fund a hire car.
I remembered that the car had been a couple of months before for a fault and the service manager told me that they replaced the Nox sensor that time. So within 5 months my car had 3 Nox sensors fitted. I think there are two within the exhaust. Luckily it was all covered with the Mercedes warranty and I have since extended it to give me some cover for what might go wrong.
It seems cars today are very complicated and expensive to repair.
My first car was a Mini some 40 years ago and the whole exhaust was £15. I am not sure you can get anything for £15 in a dealers now. Maybe screen wash but that won’t include fitting.

 

[Fenman666]

I had the adblue warning and booked the car into my local dealer. They looked at the car for the day and told me that it needed parts and the parts were on back order and the parts could be 3 to 4 months. I asked what would happen if the counter got to zero and was told that it would not start. I was not happy about this and the fact that the parts were in back order. A week later I was at 40 miles left and I spoke to the dealer who told me to call in with Mercedes Assist and then bring the car in. They would have a car for me to use whilst mine was waiting to be repaired. When I got there the service manager explained that he did not have a car available but would arrange hire one for me. Mercedes Assist gave me a lift home. I had an interesting chat on the way home and was told that there was a way of over riding the warning message. Within the week Mercedes had released the parts 2 Nox sensors and my car was repaired. I guess Mercedes were unhappy about having to fund a hire car.
I remembered that the car had been a couple of months before for a fault and the service manager told me that they replaced the Nox sensor that time. So within 5 months my car had 3 Nox sensors fitted. I think there are two within the exhaust. Luckily it was all covered with the Mercedes warranty and I have since extended it to give me some cover for what might go wrong.
It seems cars today are very complicated and expensive to repair.
My first car was a Mini some 40 years ago and the whole exhaust was £15. I am not sure you can get anything for £15 in a dealers now. Maybe screen wash but that won’t include fitting.

It seems to me that Mercedes dealerships are a bunch of crooks and the only thing consistent is their lies. If I had not sorted my nox sensor problem myself I would still be waiting even though I was “next on the list and we will get straight back to you” many months ago and still not heard a thing !

 

[Animal]

Isn't mad that there is no gauge for the adblue tank. I got my C250 bluetec preowned in 2018 and thought I'd top up with adblue before taking it to France.
Not long after that, the engine light came on and warnings that the engine would stop after so many miles!
Had to have both Nox sensors replaced at an indy. £1.5k. Fortunately the garage I bought it from helped with the costs.
I now leave the top up to my local indy on it's annual service.

 

[Smith1]

2019 GLC 250d , Going into dealer on Thursday to confirm but thats twice now and my own diagnostic reader has shown up NOx sensors , also getting spurious Adblue messages.

 

[Exprozazu]

2016 Mercedes’ glc, 50k miles. Had the engine recall software update at kings lynn , about 1K miles later the dreaded adblue message . Mercedes kings lynn said 1 nox sensor 8-12 week wait 800 quid. The part arrives 9 weeks later and I get a call saying it didn’t work we need to replace the adblue tank £1200 extra.
At the moment I’m refusing to pay until I get some contribution from Mercedes’. This has put me off of Mercedes big time, honestly think a Dacia is more reliable than this junk

 

[Fenman666]

2016 Mercedes’ glc, 50k miles. Had the engine recall software update at kings lynn , about 1K miles later the dreaded adblue message . Mercedes kings lynn said 1 nox sensor 8-12 week wait 800 quid. The part arrives 9 weeks later and I get a call saying it didn’t work we need to replace the adblue tank £1200 extra.
At the moment I’m refusing to pay until I get some contribution from Mercedes’. This has put me off of Mercedes big time, honestly think a Dacia is more reliable than this junk

Same garage !! recall for software update as I left the garage eml came on turn round head back they diagnosed nox sensor twice I tried to book in to get done but they never got back to me.

 

[jelder]

Me too, 2016 GLC 250D, 30k miles. I've just posted about it on a similar thread, the dreaded 500 mile countdown has just about expired and I'm a couple of weeks into waiting for news from the dealer on availability of a NOx sensor:

Sensor problem NOX sensor | New member introductions

Hi! New member on here although previous Merc owner. Just wondering how many of us are having what I would consider premature NOX sensor failures. I started getting an EML around 31000 miles(NOX sensor). DTC was read & cleared and the vehicle went for around 750 miles before it appeared again...

forums.mbclub.co.uk

It's fair to say that I'm not amused that a £42,000 car lasts for 30,000 miles and then simply shuts down, with MB not only denying all liability but not being able to provide parts for a repair.

 

[rOckyAMG]

My wife had the NOx sensor go twice on bank 1. It was once when the car was 3 years old c200 Se (2015) and then last year. It was replaced under warranty on both times. We have sold the car since. Apparently its a common issue on the C Class - w205.

 

[A.J.]

Is it just affecting add blue cars ??

No, mine is a Petrol and I have currently got one failed. Been waiting a couple of months now for it to be replaced. Quite a lengthy back order I am told

 

[BigEyd]

Do all the free checks first

 

[ML350mgr]

No, mine is a Petrol and I have currently got one failed. Been waiting a couple of months now for it to be replaced. Quite a lengthy back order I am told

Is there an alternative to this NOx sensor problem?

Thanks to our beloved London Mayor and his plan to extend further out the ULEZ, I'll probably be looking at a newer model but this issue with the sensors (and the cost) is putting me off a little in all honesty. Reading that GLC owners need to spend £1-2k after only few years of service is not a great for a car that I was considering buying. I thought only diesel cars had this type of sensor but apparently also petrol cars have it.

 

[A.J.]

Not that I am aware of. Although there is a lengthy back order my Indy has said that it is OK to drive albeit I do not live in a ULEZ area. I am however shortly moving into Norwich so who knows what the future for Norwich as far as ULEZ is concerned

 

[Mike9999]

had the errors on my old 2015 C300d - was just outside warranty and had 55k miles on, got MB to replace both sensors FOC on goodwill - traded the car in soon after

 

[elite_504]

2017 C200 petrol.
I bought approved used, and was comforted by the receipts for the recent dealer service, including NOx sensor. EML came on on the 200 mile journey home :-( My own diagnostic kit told me it was the nox sensor.
Supplying dealer wasn't practical for me to return it to, so embraced the network and had the misfortune to use MB Dartford, where I got a bill for £500. They refused to give the keys back until I paid. Very unhelpful attitude. Might also add it too 2 months to get the part.
I paid up, went to MB "main" customer services, and they instructed the issue of a refund- which took over 2-weeks to arrive.
First and last encounter with Dartford..
Touching wood, in nearly a year since, it's been ok.
Now that the warranty has expired, I'll be doing all my own work where I can, and using my local indy (Wright-tech Sidcup, whom I've had good service from previously) where I can't.