C220 Nox sensor and adblue Pump disaster

[sam3003]

Hi all,

I am new here so any help would be appreciated.

Sorry for the long post.

I bought a 2.1 C220 BlueTEC Sport 2014 diesel from a Mercedes dealer back in 2019 and everything was great for the first 3 years. I did more than 70K with no issues whatsoever.
Towards the end of the fourth year, I started having EML amber coming on often and took my car to an MB dealer and I did not bother about diagnostics because I had the extended warranty to cover parts.
I had the nox sensors replaced.
After my extended warranty expired (140K), I had to take the car again for the same EML
First time I was told it had to do with the AdBlue spray blockage, I collect the car and the EML was on again within a week.
I took the car again to MB and I was told that it needed some kind of software update, I collected the car again and the EML was on within less than half an hour.
I complained to the manager and I was told that the car needed both nox sensors replaced at a cost of £1200 without any contribution from MB because of mileage.
I refused to pay and told them that I don't trust MB anymore and took the car away to the MB dealer I bought the car from and I was told there that the nox sensors were fine and the problem had to do with AdBlue spray blockage (again). I was assured that the engineer is %100 about this.
I collected the car and after a month or so the EML came on again.
I felt that I did not trust MB dealers anymore so I took the car to an independent MB specialist which was recommended to me by a friend and I was the guy there who looked experienced said that he was %95 sure that the ad blue pump was the reason and that it needed replacing.
I agreed to fit a second-hand pump at a cost of £600 including labour as my car was getting old and after two weeks the EML came on again. I took the car again to the MB specialist and I was told that AdBlue spray needed clearing and that they forgot to do this when fitting the adblue pump.
I took the car again and in less than a week the EML came on again. I am going to take the car again but I am very puzzled and frustrated why no one can diagnose the problem and fix it.

Any tips as to what might be the issue here?


thanks

 

[markjay]

Welcome.

Sorry to hear about your problems.

Sadly the Mercedes Benz AdBlue system is notorious for expensive faults that can't be easily diagnosed.

Potentially the AdBlue injector might need replacing, or possibly the tank with the built-in level sensor.

The only thing I can suggest is to persevere with the independent specialist until the EML goes off again, and then trade-in the car for something else that does not have the AdBlue system.

 

[ernie]

Hi all,

I am new here so any help would be appreciated.

Sorry for the long post.

I bought a 2.1 C220 BlueTEC Sport 2014 diesel from a Mercedes dealer back in 2019 and everything was great for the first 3 years. I did more than 70K with no issues whatsoever.
Towards the end of the fourth year, I started having EML amber coming on often and took my car to an MB dealer and I did not bother about diagnostics because I had the extended warranty to cover parts.
I had the nox sensors replaced.
After my extended warranty expired (140K), I had to take the car again for the same EML
First time I was told it had to do with the AdBlue spray blockage, I collect the car and the EML was on again within a week.
I took the car again to MB and I was told that it needed some kind of software update, I collected the car again and the EML was on within less than half an hour.
I complained to the manager and I was told that the car needed both nox sensors replaced at a cost of £1200 without any contribution from MB because of mileage.
I refused to pay and told them that I don't trust MB anymore and took the car away to the MB dealer I bought the car from and I was told there that the nox sensors were fine and the problem had to do with AdBlue spray blockage (again). I was assured that the engineer is %100 about this.
I collected the car and after a month or so the EML came on again.
I felt that I did not trust MB dealers anymore so I took the car to an independent MB specialist which was recommended to me by a friend and I was the guy there who looked experienced said that he was %95 sure that the ad blue pump was the reason and that it needed replacing.
I agreed to fit a second-hand pump at a cost of £600 including labour as my car was getting old and after two weeks the EML came on again. I took the car again to the MB specialist and I was told that AdBlue spray needed clearing and that they forgot to do this when fitting the adblue pump.
I took the car again and in less than a week the EML came on again. I am going to take the car again but I am very puzzled and frustrated why no one can diagnose the problem and fix it.

Any tips as to what might be the issue here?


thanks

Welcome to the forum Sam!
Unfortunately, your experience with these systems is not unusual as the AdBlue injector can be blocked with urea crystals. There is an additive that commercial operators use that can help prevent this and if you can get the system working again correctly after cleaning and filling with fresh AdBlue, I'd try the additive. You'll find details on here if you do a search.

Some here might suggest coding out the AdBlue system, but be aware this is legally questionable.

Ernie

 

[sam3003]

Welcome.

Sorry to hear about your problems.

Sadly the Mercedes Benz AdBlue system is notorious for expensive faults that can't be easily diagnosed.

Potentially the AdBlue injector might need replacing, or possibly the tank with the built-in level sensor.

The only thing I can suggest is to persevere with the independent specialist until the EML goes off again, and then trade-in the car for something else that does not have the AdBlue system.

To be honest with you I started to seriously consider selling the car even though I was always able to get 60 mpg out of it and it was exempted from Low emission charges all over the Uk with 20 road tax. The problem is that on the one had the car only worth around 7k and a replacement car would cost me 15 to 25k.
Do you suggest I switch to diesel with no add blue or to a petrol? %95 of my mileage is on the motorway.

 

[sam3003]

Welcome to the forum Sam!
Unfortunately, your experience with these systems is not unusual as the AdBlue injector can be blocked with urea crystals. There is an additive that commercial operators use that can help prevent this and if you can get the system working again correctly after cleaning and filling with fresh AdBlue, I'd try the additive. You'll find details on here if you do a search.

Some here might suggest coding out the AdBlue system, but be aware this is legally questionable.

Ernie

The problem is I don’t know if the car has been fixed correctly as they may simple change or clean the wrong part and reset the EML which might not come on straightaway.
Thanks for the tips I will read more about them.