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CLK55 won't start - error code P0112

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by jpowell79, Sep 13, 2018.

  1. jpowell79

    jpowell79 Member

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    Your Mercedes:
    CLK W209/2003/55 AMG
    Strange issue with my CLK today. Headed off to work and car started fine, then 2 minutes up the road, I remembered that I'd forgotten something so headed back home. Pulled up outside and ran in the house to grab what I needed (was in the house all of 2 minutes) and then came back out, jumped in the car, and now I just get this noise of presumably the starter motor trying to start the engine, but doesn't actually crank.

    I have an ELM327 WiFi OBDII gizmo and an app on my phone called "FourStroke" which pulls up the error codes on the car, and I'm getting a P0112 error code.

    Feel like I'm going down the rabbit hole with this one as so far from looking on google, from what I can tell it could be the MAF sensor, the CPS, the fuel pump or an electrical fault! :-(

    What's making me think that maybe it's not the CPS is that it doesn't start regardless of whether the engine is hot or cold, and I've read that normally if the CPS is faulty, it will normally work if you let it cool down for half an hour or so. It makes no difference and still won't start even after leaving the car for two hours.

    What's making me think its' not the MAF sensor, is that most people say a MAF issue really affects vehicle performance, but won't stop the car from actually starting.

    I guess it could be the fuel pump, but wouldn't that bring up a different fault code? I can clear the P0112 code with the app, then turn the key, hear the noise and the error code comes straight back again.

    I checked the fuse in the boot for the fuel pump and that looks fine. I also swapped the relay for another identical one I borrowed from the fuse board under the bonnet (Hella 12v 4RA 002 542 26 19) that does another job, but that still didn't work so doubt it's that.

    I uploaded a quick video of the noise (unfortunately the sound isn't great - Also please ignore the 3-4 "dunk" noises at the start of the video as that's an unrelated issue of a plastic cog hidden away behind the dash that controls air-con direction...apparently a common fault on the CLK's)

    YouTube clip of car not starting

    What do you guys think?

    What I'm thinking I'll do is firstly change the CPS (this one)
    and if that doesn't work, then change the MAF (this one)

    and either of those don't work then possibly a new fuel pump?

    Any help/advice would be much appreciated!
     
  2. mrmb

    mrmb Senior Member

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    Location:
    Galway
    Your Mercedes:
    W204 C200 CDI Sport Edition 125 2011 / W215 CL600 Bi-Turbo M275 2002
    I wouldn't change anything :-D Plugin Star to it to make sure exactly what type of fault it is. You do not want to swap parts one after another, you might get it right or just replace half of the car and it will still not start. Start would definitely help here. In the mean time I would check if there is a fuel pressure in the rail. When fuel pump failed on my W203 I did not have any fuel in the rail. Before replacing the fuel pump I would check fuses, relays etc.
     
  3. Oldspanners

    Oldspanners Senior Member

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    Your Mercedes:
    C CLASS 2004 C180
    I'd start with the basics looking for a spark and then fuel.
     
  4. mioba

    mioba Senior Member

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    Your Mercedes:
    W124/1994/E200, W220/2004/S320CDI, W205/2016/C200, W447/2017/3.0 CDI
    I wouldn't mess about changing bits here and there based on a your code reader (in all due respect).

    I see time and time time again people changing many things at huge cost and not solving the problem.

    Do it once and do it right, get it on star at a reputable MB indy and find the correct cause and fix.

    don't waste your money or time it will only result in wasted money and heartache.
     
  5. mrmb

    mrmb Senior Member

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    Galway
    Your Mercedes:
    W204 C200 CDI Sport Edition 125 2011 / W215 CL600 Bi-Turbo M275 2002
    The easiest way is to connect to Star
     
  6. Oldspanners

    Oldspanners Senior Member

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    C CLASS 2004 C180
    Certainly is if you have one at your house otherwise you need to get it to a Star!
    A basic check costs nothing.
     
  7. OP
    jpowell79

    jpowell79 Member

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    Your Mercedes:
    CLK W209/2003/55 AMG

    The problem is that there are no "reputable" MB specialists where I live. My aux belt snapped a few months ago, and I called my local MB specialist who wanted £495+VAT to fix it.....I thought that was a bit steep so called around and ended up taking it to a basic "jack-of-all-trades" garage who said it was an easy job and charged me £140 including vat and the actual new belt.

    So since then I've steered well clear of the local MB specialist garage!

    I'd take it back to the local garage who did my belt but I know for a fact they don't have star, so presumably will just see the same fault code that I will see?


    If I have to trailer it to a decent MB specialist garage that are expensive (but at least they seem to be honest!) that's around 25 miles away it will probably cost me a couple of hundred quid just getting the car there and the codes read. For that amount of money I could replace the CPS and the MAF myself.

    Ahh......expensive cars and no money to spend on them...always a problem!
     
  8. mrmb

    mrmb Senior Member

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    Your Mercedes:
    W204 C200 CDI Sport Edition 125 2011 / W215 CL600 Bi-Turbo M275 2002
    Check if you have a pressure on a fuel rail. The most basic check.
     
  9. LostKiwi

    LostKiwi Senior Member

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    Your Mercedes:
    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Classic CPS failure symptom. Does it restart when cold? If yes confirms it.
    Where in the country are you?
     
  10. OP
    jpowell79

    jpowell79 Member

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    Your Mercedes:
    CLK W209/2003/55 AMG
    Doesn't restart at all, regardless of whether hot or cold.

    Anyhow I've just picket up a CPS from ECP and will have a go at it tomorrow. Just need to wait for a set of E-torx sockets from Amazon to arrive on prime tomorrow and will have a go at swapping it out.

    Might not fix it, but I've had the car the best part of 6 years and it's never been swapped, so £35 isn't the end of the world if it doesn't work.

    I'm in Essex
     
  11. LostKiwi

    LostKiwi Senior Member

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    '93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
    Well changing the CPS is good insurance if nothing else as they are a known failure point on the M112/3 engine.
     
  12. OP
    jpowell79

    jpowell79 Member

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    Well I committed to changing the CPS and what a nightmare it’s turning out to be to swap it out!

    First of all, as I’m sure many of you know, it’s a nightmare to get at. I found a “how to” that suggested using a 1/4 12in extension bar but for the life of me I cannot see how this would be physically possible as the torx screw holding down the CPS is below the plastic “D” connector on the CPS as you aim the bar down so there was no way I could get the 8E female torx socket on to it.

    Anyways after more searching around I found a far better method which is to use 2x 1/4 6in extension bars connected together with a 1/4 universal joint adaptor. That finally got me on the screw and I managed to get the thing out.

    The next issue is the CPS itself. It’s like it’s been superglued in! :-(

    I spent around 2 hours trying to pry the thing out. I even ordered these extra-long 400mm needle nose pliers to yank it out but it won’t budge at all. Nothing. Won’t twist, won’t rock, literally stuck fast.

    Will try some WD40 penetrant tomorrow all round it tomorrow, but am slowly starting to worry this will be a dropped transmission job. I dread to think what that will cost me :-(
     
  13. mioba

    mioba Senior Member

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    W124/1994/E200, W220/2004/S320CDI, W205/2016/C200, W447/2017/3.0 CDI
    Ewwww one of those jobs.
    Get some penetrating oil on it and leave. Spray again and leave.
    Jobs like this somethings need a step back and day off and bobs your uncle. Fingers crossed!
     
  14. alexanderfoti

    alexanderfoti Moderator

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    I have done a few and they can be a nightmare. Had one that needed the box to come off.

    The last one I had stuck needed to be twisted back and forth 1mm at a time, then pried up enough to get a bar and hammer the bar.

    Quick check for CPS, if live values show RPM when cranking (100+rpm) then cps is working, if it shows 0 rpm then its not!
     
  15. robparker

    robparker Senior Member Authorised Forum Supporter

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    Your Mercedes:
    420SEC, 300SL, C43, 6.9, + E320CDI v6 estate for the dog.
    Mine required box-off.. good luck!
     
  16. 00slk

    00slk Senior Member

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    Your Mercedes:
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    OMG, just chatting to a Mercedes technican and he's done them, broken off too, but used a flexi drill and drilled out the centre copper part, inserted a screw and with drew the broken part. Easy peasy. ;)
    Change the cps on a cold engine not warm :D
     
  17. LostKiwi

    LostKiwi Senior Member

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    Yep that's the method I've heard used for stuck ones.
     
  18. alexanderfoti

    alexanderfoti Moderator

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    Some cars have more space, W209's and 203's are very tight around there. W210's and 215's/220's are a bit better. I would struggle, even with a flexi drill bit.
     
  19. 00slk

    00slk Senior Member

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    It does help if you sre a contursonest....... Gee's im good at spelling :oops:
     
  20. 00slk

    00slk Senior Member

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    I look forward to changing my when the time comes :coffee:
     

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