Adblue & Nox sensor

[BarryF]

Can anyone tell me if there is a relationship between the Nox sensor and Adblue?

I have 2015 E220 Bluetec. A couple of weeks ago the orange engine light came on. I booked into my local MB dealer and they said the nox sensor had gone.

In the meantime the ECO light has been yellow(?) for some months. I pointed this out to the MB man but he said that the ECO light only changes to green under certain conditions. It certainly used to come on regularly last year.

Do I need to go back into MB for them to investigate or is this something that might change as the weather improves?

 

[tode]

Hi Barry,
It's true that the ECO function depends on many factors being met (you'll find quite a few posts dealing with the subject), but I had a similar problem on mine - the first sign was the ECO not activating (staying orange) then the engine light came on . . .
The car was put on Star, which indicated a faulty NOx sensor. Sensor changed and no problem for the last six years.

For info, the Adblue is injected into the exhaust gases to reduce the various nitrogen oxides (NOx) present and the two sensors are used to measure the effectiveness of the treatment.

 

[BarryF]

Thanks for your response. I really appreciate it. So the question is, if there is a connection between the nox sensor and the eco/Adblue do I need to go into the MB dealer?

 

[tode]

I thought from your first post that MB had already diagnosed the fault as the NOx sensor ? In which case, you should take it in to have the sensor(s) replaced.

For info, the ECO will not function if the engine light is lit.

 

[grober]

There are normally two NOx sensors [one before and one after the unit where adblue is added to the exhaust stream] to monitor the reduction in NOx content. If you do a search on NOx sensors on the forum you will get the technical details.
The adblue metering [ adding] system can fail by clogging up and the metering pump can fail but normally its the NOx sensors that fail rather than the " plumbing"

 

[BarryF]

I remember adding the Adblue some weeks ago. The orange engine light came on some days/weeks after. MB diagnosed the engine light to the nox sensor which they replaced. I pointed out to them at that time that the ECO light had been yellow for some time and they fobbed it off. What do you think?

 

[grober]

It's probably co-incidence. With these complex interactive systems the only way to trouble shoot them is using the MB diagnostic system. If the Adblue dosing system had caused the original fault that would have thrown a dosing system fault code pump failure fluid level low etc -- rather than the NOx sensor failure fault code. The early NOx sensors have a history of failures the latest versions also require a software update for example- some folks have had these renewed under warranty.

 

[BarryF]

I've booked the car in next week. Thanks for your advice.

 

[JamesPGUK]

Reg Dec 2014. 6 weeks ago local garage wanted to charge me for NOX sensor, I recall over £500. Also boot failed and wanted £600 + Wrote to Mercedes’s asking for failure rates etc and they asked me to return to the garage and it will be replaced for free. These parts should not have a warranty they should be under a guarantee.

We also run an astra with 115k never missed a beat. Really regret buying a merc nothing but issues.

 

[JamesPGUK]

I’m sure they have an emissions related warranty for 55k

 

[BarryF]

That's very interesting. What's the difference between a part under warranty and the same part under guarantee? I'm not sure how it affects me because I have already had the work done. There was not much change out of £1,000 for the nox sensor. My car is coming up to 4 years old. Currently deciding whether to keep it.

 

[grober]

That's very interesting. What's the difference between a part under warranty and the same part under guarantee? I'm not sure how it affects me because I have already had the work done. There was not much change out of £1,000 for the nox sensor. My car is coming up to 4 years old. Currently deciding whether to keep it.

Its complicated. For the first 3 years the cars parts are normally covered by the manufacturer's warranty in the UK meaning that any defective part is replaced FOC and is covered by the remaining period of the warranty. Parts that are paid for [ purchased] are usually warrantied for two years from date of purchase. Then there's "goodwill "where a part may be replaced FOC even when not covered by guarantee or warranty. This more likely when the part is known to be faulty but simply hasn't failed soon enough to be covered . Here things begin to get murky. You often hear the words "full MB service history with the same dealer" influencing the decision. In other words if you are viewed as a past and possible future revenue stream for the dealer in question it may make business sense for them to maintain that relationship and take the financial hit on themselves. Even in these circumstances the customer may asked to contribute part of the cost of the part and possibly the full [ and not inconsiderable] cost of the labour to replace it. That may also be influenced by exactly " where the buck stops" defined by who ultimately pays what -- the local MB dealer, the Consessionaire = MB UK or the Manufacturer = Daimler AG

 

[JamesPGUK]

All true and clear. My car was FMBSH and 3 years old. I purchased it from a used car dealer not merc. Always had BMW’s in the past so no history with merc. Mate diagnosed it with star at “BMW”. Local merc garage rude and unprofessional, didn’t like questions, all they could say is book it in, I sent an email to merc asking for failure rates of these parts and expected life. Rather than engage they did it for free. Maybe I was lucky. At 1k I was lucky.

Just googled Mercedes emissions warranty. It states miles so assuming it’s uk.
“our New Vehicle Limited Warranty, covering defects in material or workmanship for 48-months or 50,000 miles”

Also I mentioned guarantee rather than warranty. This was just a wish. Worcester boilers now do guarantees rather than warranties, I hope other industries follow the standard.

 

[JamesPGUK]

I’m not lucky with o2 sensor and cabin noise. Merc are having none of it. Book it in that’s all I get.

I would book it in if I had faith in the technical ability of the garage. I asked what could the noise be and could it be related to replacing the NOX sensor.....don’t know book it in.

I asked is the o2 related to the NOX issue......book it in. What’s the life of the o2..... book it in.

I will gladly book in if I’m reassured it could be x y or z each costing x y z. Wouldn’t even quote to replace o2 sensor without doing the diagnostic work at £100. I said at my risk it’s this sensor and was told I need to pay for diagnostic first.

 

[Sahida]

Reg Dec 2014. 6 weeks ago local garage wanted to charge me for NOX sensor, I recall over £500. Also boot failed and wanted £600 + Wrote to Mercedes’s asking for failure rates etc and they asked me to return to the garage and it will be replaced for free. These parts should not have a warranty they should be under a guarantee.

We also run an astra with 115k never missed a beat. Really regret buying a merc nothing but issues.

Hi purchased my car from car giant August 2018 mercedes e320 diesel Oct eco stopped working told it could be one of many things. Then engine diognosdiag light came on garage said it was related to the nox sensor but they didn't replace or repair just switched if dash light sent report to car giant. Car giant said if it lights up again then then inform them. Linn behold light came on again for engine diagnostics car giant said it's out if the 6 months warranty so I will have to pay for diognistic. Booked it In for monday with Halfords they agreed to check it out for free. If same problem as before nox sensor I will insist on car giant paying for replacement do you think MB may fix the problem without charging. How did you manage to get it dine without paying. MB charging over £200 just for diognistic. Old help

 

[Sahida]

Anyone know how long is the warranty on nox sensors I'm a very low mileage driver manily local.

 

[JamesPGUK]

Anyone know how long is the warranty on nox sensors I'm a very low mileage driver manily local.

How old is the car? Three options but far more qualified people on MB forum, it’s my view
1, email Mercedes direct asking if found to be a NOX sensor will they replace it free of charge. It’s a known issue. They will insist dealer diagnose the issue. £200 is way to high but agree with them if it is that issue they will cover all costs.

2, go to dealer with same approach, agree with them in advance if this is the NOX will they contact Merc to recover the costs.

3, some legislation changed with dealers (car giant etc) in 2015 and sales of goods etc. I’m sure they are forced to cover issues upto a year regardless of warranty. Again more informed may clear this up or search google.

Sure MB have an emissions warranty ask the dealer 50k miles or 4 years again in no expert.

 

[JamesPGUK]

If you have it in writing that the fault happened in warranty and they didn’t replace it surely they don’t have any wriggle room.

 

[JamesPGUK]

Still struggling with permanent cabin noise and intermittent o2 on off engine light.

 

[Sahida]

Hi thanks for reply car is 2015 plate only 23,900 on clock with fmbsh
The report was sent to car giant directly from Halfords as they appointed them to do diagnostic