Dying W204 - Please Help

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JBW204

New Member
Joined
Jun 18, 2021
Messages
3
Location
Essex
Car
2011 W204 Coupe C250 CDI
Hi Everyone,

This is my first post on the site, so please forgive me if I have put this in the wrong section.

I bought a C250 CDI Coupe (late 2011 model with the facelift interior) in Feb 2021 which had been running well until recently. The car was in the body shop for a week being painted, so of course was sat for 8 days in total without moving much. When I picked the car up it took 4 attempts to start the car, despite the body shop owner having just driven it in front of me. At no point did the engine attempt to tick over and no dash icons showed up. After it started up it drove completely normally.

The next day I had to drive to York (220 miles away or so). About halfway up, I pulled up at a set of traffic lights and immediately the car died on me. Again, it took 4 attempts to restart with no dash icons or attempts to tick over. I then had to pump the brake pedal so that I didn't completely come to a stop as doing such meant the car would die again. The exact same thing happened on the drive back the following day.

As a result, I called a mobile mechanic out. He checked the battery and alternator, both were fine. He also did a diagnostic test which showed up 2 stored codes, which he then cleared and reset. He also found that the DPF has been welded back together, so I can only presume at some point it was cleared out so it flows straight through. He also suggested that I should get my oil filter replaced.

I took it straight down to my mechanics for them to replace the filter, which they did. However, as soon as I got it off the forecourt it died again. Since then, every time I stop, regardless of whether the car is in Drive, Neutral or Park, it dies on me and takes a few attempts to restart.

Does anyone have any idea as to what this could be and how to go about fixing it? Understandably, I don't feel safe to drive it at the moment, so I'm keen to get to the bottom of it ASAP. Any help or advice is greatly appreciated.
 
What were the fault codes the mobile mechanic found and erased.

From your description of the symptoms I wouldn’t be surprised if it was crank sensor of fuel pressure related.
 
Welcome.

1. When you say "I bought a C250 CDI Coupe (late 2011 model with the facelift interior)" you mean that the car is the facelift model - right? I.e. not just the interior.....?

2. You say you bought it on February 2021, if so then be aware that if you bought it from a trader (i.e. not from a private seller) then you should take it back to the seller and ask that they fix it FOC - it's your statutory rights under the Consumer Rights Act 2015.

3. I doubt that the car having stood for 8 days made any difference, the timing of the fault is either a coincidence, or (less likely) the paintshop accidentally did something they shouldn't.

4. If the car was serviced by an MB dealer within the last 12 months (unlikely given the car age, I agree, but worth checking), then you can call Mobilo roadside assistance who will come-out and diagnose the fault for you FOC.

5. You should really build a relationship with a local MB specialist, generic garages aren't equipped to diagnose and fix these type of issues.
 
What were the fault codes the mobile mechanic found and erased.

From your description of the symptoms I wouldn’t be surprised if it was crank sensor of fuel pressure related.
Mmm, I can't remember exactly what they were, but one was to do with the DPF sensor and the other was something to do with low boost. Of course though, if someone did get rid of the DPF and then programmed it out of the ECU, it ought to not come up as an error code, so I'm a bit confused as to why that came up (even as stored)?
 
Welcome.

1. When you say "I bought a C250 CDI Coupe (late 2011 model with the facelift interior)" you mean that tbe car is the facelift model - right? I.e. not just the interior.....?

2. You say you bought it on February 2021, if so then be aware that if you bought it from a trader (i.e. not from a private seller) then you should take it back to the seller and ask that they fix it - it's your statutory rights under the Consumer Rights Act 2015.

3. I doubt that the car having stood for 8 days made any difference, the timing of the fault is either a coincidence, or (less likely) the paintshop accidentally did something they shouldn't.

4. If the car was serviced by an MB dealer within the last 12 months (unlikely given the car age, I agree, but worth checking), then you can call Mobilo roadside assistance who will come-out and diagnose the issue for you FOC.

5. You should really build a relationship with a local MB specialist, generic garages aren't equipped to diagnose and fix these type of issues.
Yeah, sorry should have made that clearer, it is the facelift model.

The problem I have (and maybe it's a case of silly me, my bad) is that it is the first car I've ever bought private. Even though I took an ex-mechanic with me to check the car over and got a receipt from the seller and have screenshots of the advert saying it is in perfect condition (which it turns out was untrue as I immediately had to spend £500 on suspension parts), the seller has moved out of the country. The seller had all work done by a local mechanic rather than an MB dealer too. I have got the car booked in at a specialist garage next week, but in four months the car has already cost me over £2k with getting stuff fixed, so I really begrudge spending more and more on it without knowing when it's going to end (for example, the mobile mechanic quoted me £1.5k for a new DPF yesterday but because I'm not a mechanic and have been done over by workshops before, I don't wanna just keep buying new bits not knowing if it'll make a difference. He even said it's only a 50% chance that putting in a new DPF would make any difference at all.
 

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