Power Loss After DPF Regen Attempt – W205 250d

[minhazmitha]

Hi everyone,


I’m having an issue with my W205 C-Class 250d and hoping for some advice.


It all started when the AdBlue warning light came on. I was told the NOx sensor needed replacing. Around the same time, the DPF light also appeared, indicating the DPF was clogged. I took the car on the motorway to do a regen, but while driving and revving around 3000 rpm, I noticed that after about 20 minutes, the car suddenly lost power. It definitely wasn’t pulling as it used to.


To deal with the issue, I had an AdBlue delete and DPF delete done. Later on, I changed the exhaust sensor, which made a small difference but didn’t fully restore the power.


Now, the car still feels underpowered and the engine sounds louder than usual. I was told that after the AdBlue delete, the garage should have re-tuned the ECU to properly distribute power. Could the lack of an ECU re-tune be causing the power loss?


I’m wondering if anyone else has experienced this or knows what might be causing the reduced power? Any insights or suggestions would be greatly appreciated!


Thanks in advance!

 

[toteimerced]

Check for boost leaks, both the intercooler pipes are prone to splitting, AdBlue is an after engine device, injected into the exhaust after the engine, so retuning isn’t necessary, did they unplug the AdBlue ecu in the boot? apparently this needs to be done with some deletes.

 

[pcthrillrider2]

it's now illegal to drive on UK roads

 

[markjay]

Welcome.

AdBlue delete and DPF delete - it's a bit extreme, no?

I suggest that you take the car to an independent MB specialist who has MB STAR diagnostic computer. The fault codes can then be read and the diagnostic instructions followed. This will identify the cause for the power loss.

Deleting parts of the car (and rendering it unroadworthy in the process) instead of following established diagnostic procedures is like starting with an amputation instead of a blood test....

 

[minhazmitha]

Check for boost leaks, both the intercooler pipes are prone to splitting, AdBlue is an after engine device, injected into the exhaust after the engine, so retuning isn’t necessary, did they unplug the AdBlue ecu in the boot? apparently this needs to be done with some deletes.

Hi, yes they unplug the AdBlue ECU from the boot.

 

[MSG2004]

Nox sensor fault? You've said you changed the "sensor" ie nixsensor but are there not two of them and the other could be faulty?
As Markjay recommeded, take to MB/Indy etc

 

[minhazmitha]

Nox sensor fault? You've said you changed the "sensor" ie nixsensor but are there not two of them and the other could be faulty?
As Markjay recommeded, take to MB/Indy etc

i've changed them so many times, I think every other year both sensors go faulty, which is why I decided to just delete the Ad Blue, so no nox sensor issues.

 

[Petrol Pete]

Admin , can we just bin threads about this practice ?

 

[KillerHERTZ]

As per other comments, deleting Adblue is illegal. I would go back to whoever deleted it and have a word with them, that they have made your car worthless + its not even fixed.

This isnt a discussion for on here however.

 

[ALFAitalia]

Loads of illegal mods and activities are mentioned on here....where would we draw the line!!!

 

[rf065]

it's now illegal to drive on UK roads

The true words only spoken by someone who has never spent £2 to £3 thousand attempting to fix nox sensors and an Adblue system that is not fit for purpose, only to see it return time after time!

 

[pcthrillrider2]

The true words only spoken by someone who has never spent £2 to £3 thousand attempting to fix nox sensors and an Adblue system that is not fit for purpose, only to see it return time after time!

indeed i spent nothing on my w205 as soon as the adblue problem came up i got rid of the car,brought a w203 no dpf no adblue no problems!

 

[rf065]

indeed i spent nothing on my w205 as soon as the adblue problem came up i got rid of the car,brought a w203 no dpf no adblue no problems!

So you got rid of a car with an adblue problem, meaning the value was hit or you did not tell the buyer, and bought an older car which must be worth considerably less.
You're as much a victim of the adblue system as everyone else, regardless of how it's dealt with.

 

[markjay]

The true words only spoken by someone who has never spent £2 to £3 thousand attempting to fix nox sensors and an Adblue system that is not fit for purpose, only to see it return time after time!

Karl's point was that it's an illegal mod, and therefore should not be discussed on this forum. I think it's fair to point out the potential pitfalls of these illegal mods, then leave it there. People can then do what they like with their own cars.

My own comment was regarding the fact that it seems that the OP didn't get the car properly diagnosed by a professional. All these 'deletes' are worse than playing 'parts darts'.

 

[rf065]

Karl's point was that it's an illegal mod, and therefore should not be discussed on this forum.

It's only an illegal mod to use the car on a public road, it's not illegal to carry out the mod itself and it's perfectly legal to use the car outwith the public highway, i.e., as a trackday car etc.
You cannot just ban subjects because you dont agree/like them.

 

[MSG2004]

Hope this helps others:
I got my car new in 2016
250 gle/amg-line
currently its just under 24k miles
The car has FSHMB up until this year
The nox sensor f'd up as fews day's after I had the car serviced inc adblue top-up
Cat was just out of warranty by a couple of months
MB fixed Foc
Not had the problem arise again and I am guilty of driving liss than 2 miles round trip most times - other times its 5 miles round trip -
Recent years I've added Wynns diesel additives and Wynns dpf clean on the last full tank of fuel.

When people have these conversion, what happens at the mot stage - how do they get around that?

 

[rf065]

Hope this helps others:
I got my car new in 2016
250 gle/amg-line
currently its just under 24k miles
The car has FSHMB up until this year
The nox sensor f'd up as fews day's after I had the car serviced inc adblue top-up
Cat was just out of warranty by a couple of months
MB fixed Foc
Not had the problem arise again and I am guilty of driving liss than 2 miles round trip most times - other times its 5 miles round trip -
Recent years I've added Wynns diesel additives and Wynns dpf clean on the last full tank of fuel.

When people have these conversion, what happens at the mot stage - how do they get around that?

My problems did not start until 30,000 miles, so still plenty of time for it to go wrong, and it will.
Why would it fail an MOT, the emissions in normal use are almost the same, adblue is used to clean up emissions at higher revs mainly, like high speed motorway use.

 

[MSG2004]

My problems did not start until 30,000 miles, so still plenty of time for it to go wrong, and it will.
Why would it fail an MOT, the emissions in normal use are almost the same, adblue is used to clean up emissions at higher revs mainly, like high speed motorway use.

I've seen them mot my car, they rev the car for the emissions test.
I'm no mechanic but I'm staggered a car with nox sensors deleted can pass its mot.
Anyway, I'll take your word for it as you have the car but TBH, I though these rubbish noxshits were there to reduce emissions.

 

[ALFAitalia]

Nox is not part of the MOT .....yet....Thats how. But that's likely to change and when it does there will be a lot of unhappy owners putting then back to stock and then probably selling them.

 

[Bigdrew]

it's now illegal to drive on UK roads

Maybe but how is going to know