Nox sensor upstream nightmare.

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Junaidmalik333

New Member
Joined
Oct 5, 2023
Messages
10
Location
Wolverhampton
Car
Mercedes E class 220d 2017
I have a 2017 Eclass 220d with 75000 miles. I am from Wolverhampton, Birmingham side. Few weeks ago, I had engine management light, took it to indi mercedes specialist in Birmingham. The garage told me it's upstream nox sensor fault and needs replacement. Garage replaced it with original mercedes nox sensor charged me £800. But EML came back after 70miles drive. Took it back to same garage. Garage told me it's new software update so they updated the software but fault came again with the same upstream nox sensor issue. This time garage checked again and told me they going to book me with mercedes garage and tell them to look at the sensor because it's a new sensor. Then it passed two weeks but they could not book me with mercedes garage, just kept on making excuses. Finally once the garage called me and told me they have been told by the mercedes there is a new software update so I took my car back to same garage again. The garage updated the software. Bad Luck again upstream nox sensor fault light back. Now I don't know what to do? Does anyone have the same issue? I have been thinking about making an appointment myself with my local mercedes garage but they are charging £178 for just diagnostic. But I already know the fault code. Are they going to charge me £178 just to connect with the device or I can tell them the fault code in advance. So they can just check the upstream sensor and wiring. This is my first mercedes and a diesel car so I don't know much about. Fault code:
(P300651--The nox sensor 1(cylinder bank 1) has a malfunction.)
Thanks.
 

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I have a 2017 Eclass 220d with 75000 miles. I am from Wolverhampton, Birmingham side. Few weeks ago, I had engine management light, took it to indi mercedes specialist in Birmingham. The garage told me it's upstream nox sensor fault and needs replacement. Garage replaced it with original mercedes nox sensor charged me £800. But EML came back after 70miles drive. Took it back to same garage. Garage told me it's new software update so they updated the software but fault came again with the same upstream nox sensor issue. This time garage checked again and told me they going to book me with mercedes garage and tell them to look at the sensor because it's a new sensor. Then it passed two weeks but they could not book me with mercedes garage, just kept on making excuses. Finally once the garage called me and told me they have been told by the mercedes there is a new software update so I took my car back to same garage again. The garage updated the software. Bad Luck again upstream nox sensor fault light back. Now I don't know what to do? Does anyone have the same issue? I have been thinking about making an appointment myself with my local mercedes garage but they are charging £178 for just diagnostic. But I already know the fault code. Are they going to charge me £178 just to connect with the device or I can tell them the fault code in advance. So they can just check the upstream sensor and wiring. This is my first mercedes and a diesel car so I don't know much about. Fault code:
(P300651--The nox sensor 1(cylinder bank 1) has a malfunction.)
Thanks.
You have no hope of Mercedes dealership doing anything without you paying them their fee to investigate, even though they'll come up with the answer that you already have. But once they have the fault recorded on their system they can put the details into the MB UK computer system to see if it can be repaired with a substantial MB contribution as "goodwill".

The chances then are very high that "the computer says no". Then you can, if you wish, contact MB UK directly yourself, together with the printed fault report from the dealership, and explain how you've heard very many reports about NOx sensors being replaced free because they're a known issue. Depending on the service record of your car they're likely to offer complete or part payment.

I had the sensors replaced on my car when it was 7 years old, with a £1100 contribution from MB UK. But that's after they'd been replaced foc at around 18 months old and nearly 4 years old.

Less than three years later the same fault code came up again! I couldn't be bothered with all the hassle, so I bought a cheap code reader and cancelled the code. It came up a couple of times again over the next few months, then gave up trying to get me to take any notice. I went through the same process about a year later. A big difference for me is that my car is petrol, so less dependent on having the right info being sent from the sensors. It may not be possible to 'persuade' the ECU to stop nagging. And of course, it's less likely to be chucking out lots of NOx.

Good luck.
 
You have no hope of Mercedes dealership doing anything without you paying them their fee to investigate, even though they'll come up with the answer that you already have. But once they have the fault recorded on their system they can put the details into the MB UK computer system to see if it can be repaired with a substantial MB contribution as "goodwill".

The chances then are very high that "the computer says no". Then you can, if you wish, contact MB UK directly yourself, together with the printed fault report from the dealership, and explain how you've heard very many reports about NOx sensors being replaced free because they're a known issue. Depending on the service record of your car they're likely to offer complete or part payment.

I had the sensors replaced on my car when it was 7 years old, with a £1100 contribution from MB UK. But that's after they'd been replaced foc at around 18 months old and nearly 4 years old.

Less than three years later the same fault code came up again! I couldn't be bothered with all the hassle, so I bought a cheap code reader and cancelled the code. It came up a couple of times again over the next few months, then gave up trying to get me to take any notice. I went through the same process about a year later. A big difference for me is that my car is petrol, so less dependent on having the right info being sent from the sensors. It may not be possible to 'persuade' the ECU to stop nagging. And of course, it's less likely to be chucking out lots of NOx.

Good luck.
Thanks for your reply. Could you please tell me what's the mercedes UK contact details? Did you contact by call or by email?
 
Thanks for your reply. Could you please tell me what's the mercedes UK contact details? Did you contact by call or by email?
I made the initial contact by email to [email protected]

They phoned me back and we continued there. The guy I dealt with was very helpful.
 
I made the initial contact by email to [email protected]

They phoned me back and we continued there. The guy I dealt with was very helpful.
I have sent a email on this address a month ago explaining the situation but received no reply yet. A member from Mercedes Facebook group told me to do that but he never given me the email because he forgot so I just googled it and sent the email. I hope I get a call back too.
 
I have a 2017 Eclass 220d with 75000 miles. I am from Wolverhampton, Birmingham side. Few weeks ago, I had engine management light, took it to indi mercedes specialist in Birmingham. The garage told me it's upstream nox sensor fault and needs replacement. Garage replaced it with original mercedes nox sensor charged me £800. But EML came back after 70miles drive. Took it back to same garage. Garage told me it's new software update so they updated the software but fault came again with the same upstream nox sensor issue. This time garage checked again and told me they going to book me with mercedes garage and tell them to look at the sensor because it's a new sensor. Then it passed two weeks but they could not book me with mercedes garage, just kept on making excuses. Finally once the garage called me and told me they have been told by the mercedes there is a new software update so I took my car back to same garage again. The garage updated the software. Bad Luck again upstream nox sensor fault light back. Now I don't know what to do? Does anyone have the same issue? I have been thinking about making an appointment myself with my local mercedes garage but they are charging £178 for just diagnostic. But I already know the fault code. Are they going to charge me £178 just to connect with the device or I can tell them the fault code in advance. So they can just check the upstream sensor and wiring. This is my first mercedes and a diesel car so I don't know much about. Fault code:
(P300651--The nox sensor 1(cylinder bank 1) has a malfunction.)
Thanks.
Have had the Nox sensor issue for a while now on my 2015 e class cab. First started after I took my car in for the airbag recall, when I stated that I did not want the software upgrade. A few days later the dash warning comes on, I stick a reader on it and it's nox sensor bank 1, manged to clear the code a few times before it permanently stayed on. I've been driving around for a few months now with no affect on the car whatsoever! After a lot of research, I was going to attempt to change it myself or at least clean it first, didn't seem too difficult but I'd have to get it coded. Anyway thought I'd give MB a try, wouldn't hurt to try and blag a new nox sensor, to my amazement they coughed up and are changing both FOC! Wtf! I didn't have to beg, plead or barter! Only thing was that I had to have the software "upgrade" apparently this told the tech whether the nox sensors need changing or not. Lol is what I did and said let's be frank, thing is you cannot have vehicles running around with cheat software on them, you had my car for the airbag recall and probably installed some kind of software causing the nox fault, which forces me back to Mercedes to have the software update which the tech says does increase mpg and ad blue dosage. Anyway he just smiled at my honest, conspiracy talk. Don't know if it helps but I was told on the phone that the downstream nox sensor was a recall for my vehicle but needed the software update, they had me by the goolies and left me no choice, crazy thing is that it's a 4 to 6 week wait for the sensors and my mot is up so a few weeks off the road.
MB a207 2015
No MB history but purchased from MB Wolverhampton 2018
Warning light nox sensor bank 1 4 months ago, no affect on vehicle, all as norm including adblue.
Called MB Wolverhampton who will fit FOC after software update.
 
There are several codes for NOx sensors. After having my sensors replaced twice by MB, first time foc and second time with £1k contribution, I got fed up with the hassle and had the code deleted. A couple of years later another code came up. I deleted it with my OBD reader but it came up again a month later. After repeating this for a couple of months, it gave up annoying me. 18 months later it was deja vu time. That was over a year ago and nothing again since. (BTW, this is on the M276 V6 petrol engine.)
 
Have had the Nox sensor issue for a while now on my 2015 e class cab. First started after I took my car in for the airbag recall, when I stated that I did not want the software upgrade. A few days later the dash warning comes on, I stick a reader on it and it's nox sensor bank 1, manged to clear the code a few times before it permanently stayed on. I've been driving around for a few months now with no affect on the car whatsoever! After a lot of research, I was going to attempt to change it myself or at least clean it first, didn't seem too difficult but I'd have to get it coded. Anyway thought I'd give MB a try, wouldn't hurt to try and blag a new nox sensor, to my amazement they coughed up and are changing both FOC! Wtf! I didn't have to beg, plead or barter! Only thing was that I had to have the software "upgrade" apparently this told the tech whether the nox sensors need changing or not. Lol is what I did and said let's be frank, thing is you cannot have vehicles running around with cheat software on them, you had my car for the airbag recall and probably installed some kind of software causing the nox fault, which forces me back to Mercedes to have the software update which the tech says does increase mpg and ad blue dosage. Anyway he just smiled at my honest, conspiracy talk. Don't know if it helps but I was told on the phone that the downstream nox sensor was a recall for my vehicle but needed the software update, they had me by the goolies and left me no choice, crazy thing is that it's a 4 to 6 week wait for the sensors and my mot is up so a few weeks off the road.
MB a207 2015
No MB history but purchased from MB Wolverhampton 2018
Warning light nox sensor bank 1 4 months ago, no affect on vehicle, all as norm including adblue.
Called MB Wolverhampton who will fit FOC after software update.
Hi , was the car sold to you as Mercedes approved ?
 
Have had the Nox sensor issue for a while now on my 2015 e class cab. First started after I took my car in for the airbag recall, when I stated that I did not want the software upgrade. A few days later the dash warning comes on, I stick a reader on it and it's nox sensor bank 1, manged to clear the code a few times before it permanently stayed on. I've been driving around for a few months now with no affect on the car whatsoever! After a lot of research, I was going to attempt to change it myself or at least clean it first, didn't seem too difficult but I'd have to get it coded. Anyway thought I'd give MB a try, wouldn't hurt to try and blag a new nox sensor, to my amazement they coughed up and are changing both FOC! Wtf! I didn't have to beg, plead or barter! Only thing was that I had to have the software "upgrade" apparently this told the tech whether the nox sensors need changing or not. Lol is what I did and said let's be frank, thing is you cannot have vehicles running around with cheat software on them, you had my car for the airbag recall and probably installed some kind of software causing the nox fault, which forces me back to Mercedes to have the software update which the tech says does increase mpg and ad blue dosage. Anyway he just smiled at my honest, conspiracy talk. Don't know if it helps but I was told on the phone that the downstream nox sensor was a recall for my vehicle but needed the software update, they had me by the goolies and left me no choice, crazy thing is that it's a 4 to 6 week wait for the sensors and my mot is up so a few weeks off the road.
MB a207 2015
No MB history but purchased from MB Wolverhampton 2018
Warning light nox sensor bank 1 4 months ago, no affect on vehicle, all as norm including adblue.
Called MB Wolverhampton who will fit FOC after software update.
Lucky you that they replaced it FOC. My problem has sorted now. Independent garage replaced the sensor again and now it's fine.
Did you have to pay MB the diagnostic fee for them to check the sensor?
 

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