Diesel SCR/AdBlue issues: prevention and fixes

[LynneyH]

Wonder if it’s worth taking to Merc then and asking them for a proper diagnostic. Or see if they can reset the light and get rid before it comes back.
Adblue has really put me off any diesel now.

Thats what i did 5 days ago but it came back on
First and very last diesal car for me too

 

[Tattmaylor]

Hope it all gets sorted soon!

 

[rf065]

Would never want to encourage anyone to break the law, but is it any wonder that a lot of folk are going down the £500 route, disable egr and adblue, more power and no warning lights or continuous big bills.

 

[BlackC55]

The adblue systems can be very hard to diagnose even with the right equipment. We replaced every component in a ML 250's Adblue system apart from the control unit and it still gave an engine light. We didn't charge the customer as we hadn't fixed it. Every stage of the repair we let the customer try it without a bill being produced as we knew it was going to be tricky because of the amount of codes logged. He sold it in the end so no idea what the root cause was. Cost me an absolute fortune.

 

[Tattmaylor]

The adblue systems can be very hard to diagnose even with the right equipment. We replaced every component in a ML 250's Adblue system apart from the control unit and it still gave an engine light. We didn't charge the customer as we hadn't fixed it. Every stage of the repair we let the customer try it without a bill being produced as we knew it was going to be tricky because of the amount of codes logged. He sold it in the end so no idea what the root cause was. Cost me an absolute fortune.

I would expect a decent mechanic to act as you have, even if charging for just labour and diagnostics until the problem is found. I have read from the forums that it can be very difficult to diagnose, however. Here’s hoping my Nox sensor was the only other problem and LynneyH gets their’s resolved soon.

 

[Benz17]

Did the mercedes reset the limit rather than replace the sensor

they said DPF first
EGR
mass flow sensor
Adblu injector
Filter
Nox sensors
Adblu injector again
Adblu pump
After each fix the light came on again in less than a mile. Almost like they were chasing it around 7k so far

I am sorry for you, but I don’t think you have taken it to a proper Mercedes Indy, especially one who comes recommended on here. It could be there isn’t one near you.


Edit. Just read BlackC55 comments, so I guess my comment is incorrect.

 

[Tattmaylor]

It does sound like they are trying everything piece by piece to find the problem, but as BlackC55’s comment above, it can be difficult to find the root cause of Adblue issues, and no way should they keep charging if parts didn’t need replacing.
Is there a thread of Indy garage recommendations on here? Or could someone point me in the right direction?

 

[LynneyH]

The adblue systems can be very hard to diagnose even with the right equipment. We replaced every component in a ML 250's Adblue system apart from the control unit and it still gave an engine light. We didn't charge the customer as we hadn't fixed it. Every stage of the repair we let the customer try it without a bill being produced as we knew it was going to be tricky because of the amount of codes logged. He sold it in the end so no idea what the root cause was. Cost me an absolute fortune.

Everything i listed is now replaced the last being the adblu pump. In the last 3 months 7k altogether the light is out now AGAIN. For how long.. one can only hope

 

[LynneyH]

Would never want to encourage anyone to break the law, but is it any wonder that a lot of folk are going down the £500 route, disable egr and adblue, more power and no warning lights or continuous big bills.

I totally get it. I am all for saving the environment but 7k in 3 months i won't say in polite company what the environment can do at the moment

 

[LynneyH]

Hope it all gets sorted soon!

The adblu pump replaced 1k. The had light been off a day, so far so good

 

[CaptainPugw4sh]

Well, after far to many trips to the garage and far to much spent, the car dealership I bought mine from agreed to take it back and I'm now back in a Volvo XC60 D4 which I have to say, is just head and shoulders above the Merc in every respect. So I guess that's it for me. Don't think I'll ever go for a Merc again as this whole experience has put me of the brand completely.
Wisjing you all good luck in getting yours fixed, but for me it's goodbye.

 

[JHS]

Well, after far to many trips to the garage and far to much spent, the car dealership I bought mine from agreed to take it back and I'm now back in a Volvo XC60 D4 which I have to say, is just head and shoulders above the Merc in every respect. So I guess that's it for me. Don't think I'll ever go for a Merc again as this whole experience has put me of the brand completely.
Wisjing you all good luck in getting yours fixed, but for me it's goodbye.

Each to his own, but I went from an XC60 to a C250d which I found head and shoulders above the Volvo. Blocked DPF, self igniting inlet manifolds and failed balancer shaft issues did it for me.