Ongoing EML issues

[davg]

Morning all,

We have been having ongoing issues with my wife’s w205 c250d. Annoyingly, we did not initially have a warranty so it has cost us a fair bit! It is a Jan 2015 car with 65k on it, so did not expect it to cost so much in repairs. We are only 2nd owners (bought it at 3 years old from MB dealer) and it has FMBSH.

Rough timeline:

September time last year - EML. MB diagnose NOx sensor. Had this completed by a specialist with MB part.
October - EML returns. Diagnosed by MB roadside as Turbo Exhaust gas sensor. MB specialist replaced this too.
December - EML returns. Run in to MB. They diagnose that AdBlue was over filled. Funnily enough, the EML came on when the only people who had touched the car was MB dealer and they topped up the adblue. Admittedly, I then did top it up myself and probably overfilled, but that was as it was counting down!
January - EML light back on again. They tell us that it was low quality of AdBlue being used. Again, apart from the tiny top up, they are the only ones who have topped out up!
February - EML light on again. They diagnose AdBlue pump failure. Replaced by MB.
February, 150 miles later - EML back on! This time they say that there is a fault code that will not disappear and they have had to contact MB HQ or something or other. (Message relayed from my wife, I am waiting for them to call today)

Obviously, really disappointed in the whole situation. It has cost us a fair few thousand pounds to get nowhere. I strongly suspect that there has been an underlying issue that has not been diagnosed. It certainly seems like the £1000+ on a new AdBlue pump was unnecessary as we got less than 150 miles before EML came back on.

Just wondered if anyone had any advice as to what to do or can spot a particular issue that it could be? I am keen to recoup some costs. We have ordered her a new car (a BMW, given our experience now) and whilst we have a good trade in price on the car, I would prefer to sell privately with the Merc Warranty that is on it now. I don’t want to trade a duff car or sell someone a car that is not repaired though as we just don’t do stuff like that!

Also just wanted a bit of a rant..... thanks for listening!

davg

 

[davg]

Forgot to mention, in late Jan it went in for it’s major service and nothing came up.

 

[markjay]

Sorry to hear about your trouble.

You say: "Annoyingly, we did not initially have a warranty.... bought it at 3 years old from MB dealer".

Does this mean that the issues started after the 1-Year MB Approved Used warranty expired?

And, not criticising, just asking - why did you keep going back to the same dealer, given their poor track record at diagnosing and resolving issues? Surely there are plenty of dealers, as well as independent specialists, in your area?

 

[Jigglyjohnson]

Do you have the past paperwork from the dealers you have been to with the fault codes at the time ??

 

[davg]

Unfortunately not— didn’t think that it would be something we would need to do!

Will the ‘star’ system, or whatever they call it, not have a log of everything done on the car, including fault codes raised by diagnostic?

 

[Petrol Pete]

Hi Dav , if you want to rant about a 5 year old Diesel Mercedes Benz with just 65K miles on it going horribly wrong and costing you money you have come to the right place. You are not alone , rant away and many on here with similar tales of woe will be along soon. You have come to the right place for sound advice.

I hope it all works out OK for you. Best of luck

 

[davg]

Sorry to hear about your trouble.

You say: "Annoyingly, we did not initially have a warranty.... bought it at 3 years old from MB dealer".

Does this mean that the issues started after the 1-Year MB Approved Used warranty expired?

And, not criticising, just asking - why did you keep going back to the same dealer, given their poor track record at diagnosing and resolving issues? Surely there are plenty of dealers, as well as independent specialists, in your area?

Yes - the warranty ran out some time ago and didn’t think that it would be worth having one (how wrong we were). Assumed that a fairly mass produced, premium car that is not performance/does not have high stress components would not cost so much!

Have returned to the dealership partly as hoping to have some leverage to get things resolved.

 

[Jigglyjohnson]

Keep us all posted on the fault codes the dealer pulls from the car ask them for a copy of the short test. C class 205 have mainly issues with nox sensors and some wiring issues where water has got into the nox sensor plugs and can cause all sorts of weird faults all which lead to the eml coming on. A full test can be carried out on the adblue system including the pumps and injector nozzle and the nox sensors. Would of thought they should have done this to rule out no underlying issues. Also the wiring to the adblue pump/module can chafe on the under tray that covers the pump and can cause faults with the adblue pump or metering system this should also be checked

 

[davg]

Many thanks for this, Jigglyjohnson. Will certainly raise this with the dealer and ask for prinouts of all fault codes via email.

I would not be surprised if the NOx sensor, temp sensor and AdBlue pump were all due to something along the lines of the above. If so, I am doubtful that I will be able to get much traction on refunds as it’s impossible to prove! If I can at least ensure no more costs and ideally not claiming on the extended warranty I have taken out (so I can cancel it for pro rate refund), I’d be appeased.

Not going to rush back to Mercedes though, which is a shame. Would have considered a GLC43 or E53 to replace the c class, but certainly not now! Had been considering a C63s to change my car to next year too but the memory will still be too fresh, I think!

 

[davg]

Just spoke with the dealership. They had to send off a load of data to MB HQ as they couldn’t work out what it was telling them. Something to do with data from the NOx sensors.

MB HQ got back to them and asked for some specific data/information which they provided immediately. Hopefully should know more tomorrow morning....

 

[davg]

Have heard from the dealership today. MB HQ have responded twice to them asking for more data. The dealership suggested that it is good news that they have been so quick in responding (within hour/s).

Not sure that is such a good sign to me.....

 

[JEHOVAH]

Hi Davg. These models the 2015 Mercedes C class seems to be well know for this Nox sensor issue and also the frequent coming on of the EML. Pain in the neck is an UNDERSTATEMENT. I bought my Merc from a Mercedes dealer in London and b4 I go home, the EML came on. Called the dealer and was told to return the car back to London and that they would have to fix it. Now this was the start of my EML trouble. Well the EML went off a few days later because I couldn't go through the trouble of driving back to London. Took it to a Merc specialist who told me that I should just keep on driving until the EML remains permanently on which happened a few months down the line. Took it to them again and was told it is something to do with DBF which was sorted out. Cost me between £500 and £600. EML came on last week again on my way to work. Called the AA and he said it an adblue sensor. Was advised to take it to a workshop. It was due for annual service 4 days ago at Halfords. Halfords put the diag on it and said it was the Nox sensor and advised I take it into the dealership. Called to book an appointment and took it in today. Was quoted £922 for everything. Just for the record, the car is no longer on warranty. Read on here to find out if my car was on recall, so I called MB head quarters at Milton Keynes and was told my car was actually on recall for (Check & replace Nox sensor if necessary). Was giving this code(SMPC760/4985) to give to the Mercedes dealer repairing it. Went straight there only for the guy to say he was going to check. He finally said I wouldn't have to pay for it and said most of these 2015 model have been recalled for this same issue with the Nox. Never had a car that the EML say good morning to one every other day. Thinking of getting rid of it. Have only had it for a year with 89k on the clock and really getting fed up of it. I reckon it is the worst make Mercedes has ever produced. Might try BMW. Got a 2012 Merc C Class as well and have only had the EML come on once since I have had it going to 3 years now.

 

[AustinP]

Hi Davg. These models the 2015 Mercedes C class seems to be well know for this Nox sensor issue and also the frequent coming on of the EML. Pain in the neck is an UNDERSTATEMENT. I bought my Merc from a Mercedes dealer in London and b4 I go home, the EML came on. Called the dealer and was told to return the car back to London and that they would have to fix it. Now this was the start of my EML trouble. Well the EML went off a few days later because I couldn't go through the trouble of driving back to London. Took it to a Merc specialist who told me that I should just keep on driving until the EML remains permanently on which happened a few months down the line. Took it to them again and was told it is something to do with DBF which was sorted out. Cost me between £500 and £600. EML came on last week again on my way to work. Called the AA and he said it an adblue sensor. Was advised to take it to a workshop. It was due for annual service 4 days ago at Halfords. Halfords put the diag on it and said it was the Nox sensor and advised I take it into the dealership. Called to book an appointment and took it in today. Was quoted £922 for everything. Just for the record, the car is no longer on warranty. Read on here to find out if my car was on recall, so I called MB head quarters at Milton Keynes and was told my car was actually on recall for (Check & replace Nox sensor if necessary). Was giving this code(SMPC760/4985) to give to the Mercedes dealer repairing it. Went straight there only for the guy to say he was going to check. He finally said I wouldn't have to pay for it and said most of these 2015 model have been recalled for this same issue with the Nox. Never had a car that the EML say good morning to one every other day. Thinking of getting rid of it. Have only had it for a year with 89k on the clock and really getting fed up of it. I reckon it is the worst make Mercedes has ever produced. Might try BMW. Got a 2012 Merc C Class as well and have only had the EML come on once since I have had it going to 3 years now.

Just to addI had the Nox sensors fail on my c220 w205. I went into the dealers with an armful of evidence of failures from the Internet and merc derby did them all for free. Unfortunstrly I got the software update for the cheat mode too and lost 4mpg

 

[davg]

Finally had a response from Mercedes. They are now changing both NOx sensors, free of charge. They will do the work today and then run lots of tests tomorrow and extract data to send back to MB in Germany to ensure it is actually fixed.

Once all of that is done, I will discuss with them whether or not the AdBlue pump needed to be changed and if there is a reasonable expectation to have some money back from that work.

Main thing is, fingers crossed it actually fixes it!

 

[tombell]

Bought a 62 Plate Merc ML at the beginning of May. A week ago I got message something like "1,700 miles before AdBlue runs out". I filled AdBlue to the brim. EML light still on. Tried all the tricks on the web to turn it off. No Go. Next day "600 miles engine won't restart". Took it to MB Oxford today. They are getting 2 Nox sensors for the end of the week. They want £1,871.52. and will have to remove exhaust. 3.8 hours
Does anyone have the part numbers for the nox sensors and the adblue tank