AdBlue message back on after being checked and reset at Mercedes !

[lorri66]

hello, I know there's so much written on adblue but still want to ask.
Adblue message on a couple weeks back but still had 4000miles in the tank, half full. I did top up which took me to 6000 but this didn't stop the message or turn off the EML.
Had it checked locally as it was MOT time, they possibly thought pump and managed to turn EML off and the message for the MOT, it lasted 3 days then all came back on again. As I already had it booked at dealership for service I thought I'd let them do full diagnostics, that was yesterday.
The good news came back as that it was just needing a reset after I topped up the adblue without engine being on, they said I definitely won't have any more issues with it and nothing serious. Guaranteed it was all good. drove home, about 40mins.
Well this evening after a quick journey of about half a mile the EML is back and the check adblue message!!! the count down hasn't started yet but I'm expecting that as that was on yesterday before Mercedes serviced and checked it.
How can their diaganostics get it wrong or miss something more serious when they plug in to get the fault codes whilst EML is on and adblue message is on dashboard???
Its a E Class 220d dec 2016 (WWD213) only done 55k and I've had for 5yrs without this message ever happening before.
feeling a bit peeved that main dealership got it wrong and now wary of using the car over the xmas break.

 

[markjay]

Unfortunately AdBlue issues can be fiendishly difficult to diagnose. And, expensive to fix as you are probably aware.

My advice is to do what needs to be done to get the EML turned off, then quickly trade-in the car for a W205 petrol.

Sorry if this is not what you wanted to hear.

 

[lorri66]

Thank you but with EML only off for one journey theres not much hope of trading it in that quick!! Plus i actually really like my car, £20 tax & lovely cream interior seats, gives good miles to the gallon & very comfy.
Hopefully if it can be diagnosed correctly it can be fixed first time.

 

[lorri66]

Just another thought… i’ve had the battery changed twice in the last 5weeks (ATS mess up with the first one) could this have triggered something??

 

[ALFAitalia]

Maybe......but more likely is just that Adblue is an inherently flawed and unreliable system....and unfortunately it seems that Mercs one is one of the worst. £20 VED and good mpg do becomes a bit irrelevant of the car needs a thousand pounds plus Adblue repair every year or so! Take the above advice and fix it and get rid.

 

[lorri66]

I’ve had it 5yrs & its 7yrs old only done 55k so really it should have plenty of running years left. I love it, its an estate so got lots of space for what i need. Until now i’ve not had too much go wrong on it. I cannot afford or probably find a similar car of same mileage & tax thats a good price without the adblue.

I will get it fixed but just didn’t understand why the merc diagnostic said just a reset needed. The only message i have is ‘check adblue’. If i keep driving it no doubt i’ll get the count down mileage before it wont start.

 

[zipdip]

Well you have a car that needs using given the mileage it has sat on your drive for long periods and that adblue forms crystals that block the pump,as AlFAitalia has said the merc system is a poor one suggest you find a merc indy and get them to do the work it will be a bit cheaper but the bill will be big just looked on ebay and a adblue tank for your car is over £900

 

[tode]

Hi Lorri, while it's true that there have been quite a few posts about problems with the Adblue system, there must be thousands out there with no problems. I've had no problems with it over 10 years, and only do about 6000 miles a year. If the car is in good condition and you like it, then I would seriously consider getting it sorted and keeping it.
Some of the points in your first post seem strange to me:
- When you say "Adblue message", do you mean Adblue low ? If so, that could be normal.
- But then you say "Range 6000 after filling", this surprises me - mine does about 16000 miles on a 25 liter tank. Do you know the capacity of your Adblue tank?

 

[lorri66]

Hi Tode
yes I've not had any issued before this, and seems coincidental that I had a new battery and this happened a couple of days later.
I do about 7000 miles a year and I have no intention to be trading in, its comfy and the interior colour that makes me feel bright! its not not black.
the message says check adblue but the info says I have 8000mile and a full tank (topped up by Mercedes on Thursday). the initial message was when the tank was half full so I was still surprised to get it. The EML is orange.
I don't know the capacity and I've never topped it up before as its always been done as part of my service.
like is his just odd that the actual Mercedes technician said I won't have any more issues as it was needing a reset after I added adblue without the engine running but this still seems incorrect as why would I get a warning when there is still half a tank of adblue!! I did ask but never got a proper answer.
It would be ok if the 500mile message didn't kick in after a few drives, this panics me as apparently it literally would not start if the count down got to zero.

 

[tode]

If you fill up with Adblue after getting the "Adblue low" message, you don't need to reset anything (whether the engine was running or not). I've never heard of having the engine running when filling up !
It sounds to me as though the Adblue level sensor is playing up, but I have no idea where it's hidden . . .
I always do my refills myself because imho everything must be scrupulously clean.

 

[markjay]

If you fill up with Adblue after getting the "Adblue low" message, you don't need to reset anything (whether the engine was running or not). I've never heard of having the engine running when filling up !
It sounds to me as though the Adblue level sensor is playing up, but I have no idea where it's hidden . . .
I always do my refills myself because imho everything must be scrupulously clean.

It's an acoustic sensor located inside the AdBlue tank, and it is not sold separately. Replacing the sensor (and the AdBlue tank) is a four figure job. One way around it to to buy a second hand AdBlue tank off eBay from breakers (and potentially move only the sensor across to your tank), but the obvious issue is that you don't know the condition of the second hand sensor or how long it will last. And what compounds matters is that often replacing the obvious part doesn't actually solve the problem, at which point you need to keep throwing good money after bad money.

As for people not wanting rid of AdBlue cars that have shown no sign of fault, fair enough, but once AdBlue reared it's ugly head and you've had an AdBlue fault and EML, keeping the car beyond that point is tempting faith. AdBlue issues rarely go away on their own, and there's rarely a quick and cheap fix.

 

[tode]

I agree with you Markjay, but I just wonder how many of the Adblue problems are down to 'cheap' fixes: Ebay sensors, cheap Adblue, dirty products/containers . . .
Plus it's (relatively) recent technology that many garages seem to have difficulty to grasp. Logically, an Adblue problem, if correctly diagnosed, should be resolved by changing the correct part.
Maybe I'm just a silly old optimist at heart . . .

 

[MSG2004]

I'm pretty sure its the noc sensor as my probs started soon after ad blue added to car by dealer at just over 3 years old and full MBFSH - i requested Foc and thankfully got that

 

[W1ghty]

Hi Tode
yes I've not had any issued before this, and seems coincidental that I had a new battery and this happened a couple of days later.
I do about 7000 miles a year and I have no intention to be trading in, its comfy and the interior colour that makes me feel bright! its not not black.
the message says check adblue but the info says I have 8000mile and a full tank (topped up by Mercedes on Thursday). the initial message was when the tank was half full so I was still surprised to get it. The EML is orange.
I don't know the capacity and I've never topped it up before as its always been done as part of my service.
like is his just odd that the actual Mercedes technician said I won't have any more issues as it was needing a reset after I added adblue without the engine running but this still seems incorrect as why would I get a warning when there is still half a tank of adblue!! I did ask but never got a proper answer.
It would be ok if the 500mile message didn't kick in after a few drives, this panics me as apparently it literally would not start if the count down got to zero.

Might be worth trying ….pump out the adblue and refil with fresh newly dated adblue with a forte anti crystal additive .

 

[Gollom]

All this talk about the MB adblue system - surely they are selling a car "not fit for purpose"? Has anybody taken this further? I am thinking the rear subframe issues which MB seem finally to have acknowledge (although not when I had to shell out to have Mrs. Golloms R171 sorted!!)

 

[lorri66]

Gosh!
well I managed to speak with the dealership today that serviced it on Thursday and its booked in for next Friday for further investigation but she said could well be the NOX sensor.
I have driven it today and the message disappeared but EML remains on. After stopping and restarting the message comes up but then goes away and no messages present in service section on dashboard.
who knows what the issue is.
the service lady told me I can ring RAC as I have Mercedes cover and they can do a diagnostic as use the same equipment if I want to get the EML turned out and adblue reset. Think I'll just wait until next week unless I break down on a journey of course.

 

[tode]

Have you had the diesel update done by them ?

 

[markjay]

Gosh!
well I managed to speak with the dealership today that serviced it on Thursday and its booked in for next Friday for further investigation but she said could well be the NOX sensor.
I have driven it today and the message disappeared but EML remains on. After stopping and restarting the message comes up but then goes away and no messages present in service section on dashboard.
who knows what the issue is.
the service lady told me I can ring RAC as I have Mercedes cover and they can do a diagnostic as use the same equipment if I want to get the EML turned out and adblue reset. Think I'll just wait until next week unless I break down on a journey of course.

I think the people you should call in the event of a breakdown are Mobilo, this is the Mercedes Benz official roadside assistance service (who probably use the RAC as subcontractors) - 00 800 1777 7777.