C207 - Engine light - MOT fail - Help!

[MissVix]

Hi,

My car: 2016, E220d coupe (C207).

Back in Nov I had an accident at 3mph- broken headlight and bumper. My insurance company, Direct Line, fixed it and when they handed it back the engine light was on. Though they said it's nothing to do with the accident so they can't fix it, they sent someone round to diagnose the code and he said it was DPF related and I'm 99% sure he said it was to do with O2 or X20 and that was a minor job that should cost £50-£80.

I put it on the back burner to get Christmas out of the way and then I changed jobs late 1st Feb.

Fast forward to mid Feb: I had 5 weeks left on my MOT and went to my trusted mechanic to sort the repairs and MOT. Long story short, over several week and despite reassuring me all will be fine, he's not been able to identify the issue, revealed he doesn't have full Merc diagnostic tools, but thinks it's related to O2 and possibly the ad blue injector failing - meaning the car is at risk of being blocked up and not being able to start, thereby requiring a new DPF at a cost of about £2500.

If I'd known this a month ago when he first inspected my car I would have had plenty of time to find an alternative option. Instead I am left with less than 2 weeks to get my car fixed and MOT'ed and I don't even know what the problem is. I also do not have the luxury of getting to work without my car nor taking annual leave. I have 2 Mercedes-specialists garages I could try but could you advise of the likely issue, if my mechanic was talking sense/nonsense, and the costs I'm looking at?

I want to cry....

 

[KennyN]

No point guessing , can turn into an expensive exercise as an EML could be loads of things.

Proper diagnostic is required by someone who has the correct equipment and the knowledge to use it.

K

 

[MissVix]

If it is the DPF do you have an idea of cost to replace? I've tried Googling to no avail.

 

[KennyN]

If it is the DPF do you have an idea of cost to replace? I've tried Googling to no avail.

There are loads of new ones on eBay from £250>.

If it isn`t the DPF then you have just wasted money , hence the advice to get the codes read.

Unusual for the DPF to need replaced , they can be blocked and just require cleaning to get them operational again but the reason it is blocked will need to be investigated , if that is what the issue is.

K

 

[markjay]

The DPF and AdBlue are two separate systems.

The DPF, as KennyN said, can generally be cleaned, but the cause for it getting blocked in the first place needs to be identified. It could be something as simple as the car only being used for short journeys, in which a regen can be forced using a diagnostic tool, or could be an issue with the DPF sensor etc.

The AdBlue system is the one that can start a countdown and eventually leave you stranded. Unfortunately, faults with this system can be expensive to fix.

Also, on these cars, faulty NOx sensors are quite common, but I would have expected your mechanic to be able to work this out if this was the cause.

You really need to take the car to an MB socialist who has the MB STAR diagnostic computer (and knows how to use it).

 

[MissVix]

The DPF and AdBlue are two separate systems.

The DPF, as KennyN said, can generally be cleaned, but the cause for it getting blocked in the first place needs to be identified. It could be something as simple as the car only being used for short journeys, in which a regen can be forced using a diagnostic tool, or could be an issue with the DPF sensor etc.

The AdBlue system is the one that can start a countdown and eventually leave you stranded. Unfortunately, faults with this system can be expensive to fix.

Also, on these cars, faulty NOx sensors are quite common, but I would have expected your mechanic to be able to work this out if this was the cause.

You really need to take the car to an MB socialist who has the MB STAR diagnostic computer (and knows how to use it).

There are loads of new ones on eBay from £250>.

If it isn`t the DPF then you have just wasted money , hence the advice to get the codes read.

Unusual for the DPF to need replaced , they can be blocked and just require cleaning to get them operational again but the reason it is blocked will need to be investigated , if that is what the issue is.

K

Inbetween posting my ad and reading your reply, I located a deep flush process at National (via Halfords) for £85. Is it recommended to do this before getting it checked out - to see if it removes the engine light and allow me to get my MOT done? Another reason I'm thinking of this is that I don't want to take my car with the warning light to a specialist and be told I need lots of expensive work that I don't actually need (as happened at Charlie Browns back in the day).

The DPF and AdBlue are two separate systems.

The DPF, as KennyN said, can generally be cleaned, but the cause for it getting blocked in the first place needs to be identified. It could be something as simple as the car only being used for short journeys, in which a regen can be forced using a diagnostic tool, or could be an issue with the DPF sensor etc.

The AdBlue system is the one that can start a countdown and eventually leave you stranded. Unfortunately, faults with this system can be expensive to fix.

Also, on these cars, faulty NOx sensors are quite common, but I would have expected your mechanic to be able to work this out if this was the cause.

You really need to take the car to an MB socialist who has the MB STAR diagnostic computer (and knows how to use it).

If a clean can unblock the DPF - removing the issue - why would there still be an need to investigate the cause?

Can you give me an idea of how expensive you're talking re: Ad Blue system?

NOx! I think that is what I was initially told by Direct Line. I knew it wasn't O2 as I know what that is and I also remembered an "X" being mentioned. If it is something as simple as NOx sensor, are most garages going to tell me that (which I'm guessing is cheap-ish to fix) or blag me for a whole lotta pointless work?

 

[ernie]

Inbetween posting my ad and reading your reply, I located a deep flush process at National (via Halfords) for £85. Is it recommended to do this before getting it checked out - to see if it removes the engine light and allow me to get my MOT done? Another reason I'm thinking of this is that I don't want to take my car with the warning light to a specialist and be told I need lots of expensive work that I don't actually need (as happened at Charlie Browns back in the day).



If a clean can unblock the DPF - removing the issue - why would there still be an need to investigate the cause?

Can you give me an idea of how expensive you're talking re: Ad Blue system?

NOx! I think that is what I was initially told by Direct Line. I knew it wasn't O2 as I know what that is and I also remembered an "X" being mentioned. If it is something as simple as NOx sensor, are most garages going to tell me that (which I'm guessing is cheap-ish to fix) or blag me for a whole lotta pointless work?

The NOx sensors are an easy fix, but replacing both will cost about £1200 - 1400. Hence the advice to have the codes read by someone who knows what they are doing with an MB diagnostic tool. Otherwise, you're throwing money to the wind in a guessing game. AdBlue problems can cost nearer £2000 to put right. Hence money spent at at an MB Specialist is money well spent.

Ernie

 

[Bobby Dazzler]

I sense that you don’t trust garages based upon a previous bad experience. Whereabouts are you, because we have several well-respected specialists on the forum?

 

[OneForTheRoad]

You wanna stop asking your trusted mechanic tbh . Go seek a diagnosis from one of the merc specialists you know of . Ad blue has nothing to do with the dpf , the O2 sensor measures oxygen and works with the maf's to regulate fuelling. Your dpf may just need a regeneration , do you only do short journeys??

 

[KennyN]

Is it recommended to do this before getting it checked out - to see if it removes the engine light and allow me to get my MOT done?

IF the DPF is blocked then it has done so for a reason , cleaning it without resolving this reason is pointless as it will only happen again.

There are many MB specialists around the country , someone on this forum will have had a positive experience of one close to you and should be able to point you in their direction.

K

 

[Stratman]

Offhand I can't think of any good indies on the moon

 

[mercmancdi]

Is there any good mappers in your area could diagnose and if required map the nox sensors out thus no more ad blu either .maybe not ideal to some but I have had it done in past with great results.

 

[KennyN]

Offhand I can't think of any good indies on the moon

Has "Aldrins Automotive" closed , not surprised as there was no atmosphere - no real buzz around the place.

K