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W220 S320 CDI - Limp Mode, EPC Warning

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by Lord_Langers, Jan 27, 2018.

  1. Lord_Langers

    Lord_Langers Member

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    Your Mercedes:
    2005 S320 CDI
    Hello all,

    Well, the honeymoon period is definitely over with my new W220. She's a 2005, with the OM648 I6 engine and 140,000 miles.

    Coming home from work on Thursday evening, I slowed down from 70mph at a set of traffic lights, and when I went to pull away again, the car was obviously in limp mode - slow acceleration, gearbox goes up through the gears quickly and will not change or kick down, and revs in neutral limited to 3,000 RPM. When I got back, I restarted the engine to see if it would clear - but it did not, and the "El. Power Control EPC - Visit Workshop!" warning light came onto the display.

    So today, I plugged it into my generic OBD2 reader, and read the code: P1408 - EGR System Flow out of KOER Self Test Range.

    Thinking it would just be a clogged up EGR valve (the previous owner only did short trips), I removed it today and gave it a good clean (including the mechanism under the black plastic cover, which was actually more clogged than the valve itself), thinking it would solve the issue. However, the fault code persists and re-appears every time the car is started.

    When the code is cleared, upon the first start the "EPC" warning isn't there, but the car is still in limp mode. As soon as it is restarted, the EPC warning comes back.

    I also just cleaned out the MAF sensor using some brake/clutch spray, which did indeed look pretty dirty - however, it made no change.

    My reader also allows viewing of Live Data, including the MAF sensor reading. At a warm idle (~700rpm), the MAF reports around 18 g/s (approx. 2.2lb/min). Does anyone know is this is about right for this car?

    Anyone got any experience with similar symptoms, or any suggestions?

    Many thanks

    Sam
     
    Last edited: Jan 27, 2018
  2. Craiglxviii

    Craiglxviii Senior Member

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    Location:
    Cambs UK
    Your Mercedes:
    W215 CL500 Garage Queen; W211 E320 Avantgarde Estate Designo Edition
    Hi Sam.

    Your genetic OBD2 reader will not work on an MB. You will need to get the car to a local Indy and plugged in Star, the MB diagnostic system in order to check fault codes.
     
  3. UKMarine

    UKMarine Senior Member

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    Location:
    Durham
    Your Mercedes:
    2005 S320 L cdi
    Hi,

    I’ve just bought an S320 cdi on a 55 plate in black with an el power epc fault (is yours black too) I did this on purpose (I know I know) but I like a challenge, luckily I don’t use it as I have another car so it’s there until fixed.

    I did a lot of homework before purchase and the concensus is (rightly or wrongly) that it’s the fuel system playing up. First off change the fuel filter as even a small blockage can alter the fuel pressure trim and throw up a fault, secondly it could be the fuel pressure sensor at the end of the fuel rail, thirdly start the car and listen for the fuel pump in the tank, if you can hear it then fine, if not, well not fine but at least you know. After those three it gets progressively oilier, as in it could be the high pressure fuel pump sucking in air or more noticeably leaking out fuel, can you smell diesel in the cabin or out in front of the car? Then it could be down to the injectors leaking down a bit too much.

    Anyhoo there’s a bit to be going on with, not definitive I realise and could be barking up the wrong tree but I did a lot of research and it nearly all came up with fuel. I would really recommend that you seek the services of an independent and get it hooked up to their Star system and get the real codes read, I’m not a fan of these cheap home user diagnostics as they tend to give the wrong diagnosis, but in the ball park. Yours is giving EGR, exhaust gas which could be too thick and sooty due to the car being in limp mode because of something else...... I don’t know but have a change of your fuel filter and O rings, at least it’s cheap to do and can’t do anything else but help. Then if it doesn’t sort it get it into an Indy to have it plugged in.

    Good luck

    Simon
     
  4. Craiglxviii

    Craiglxviii Senior Member

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    Your Mercedes:
    W215 CL500 Garage Queen; W211 E320 Avantgarde Estate Designo Edition
    Sam/ Simon.

    Learning point- get it plugged in FIRST!
     
  5. UKMarine

    UKMarine Senior Member

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    Your Mercedes:
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    Ha. Point taken....it’s the Land Rover owner in me. Smash it into submission with a 5kg fine adjustment tool :D
     
  6. Craiglxviii

    Craiglxviii Senior Member

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    Yeah, I tried that to start with. Didn’t work. Then I spent £120 on an iCarsoft i980 OBD/2 reader specifically for MBs, best investment I ever made. Then I saw what Star could do- these cars are made to have faults diagnosed on a computer first; chasing faults through replacement will just result in wallet-raping.
     
  7. UKMarine

    UKMarine Senior Member

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    Your Mercedes:
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    There is an outfit a few miles from here but they use the Xentry3 system, how does that stack up against the Star system or are they the same?
     
  8. Craiglxviii

    Craiglxviii Senior Member

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    That will work!
     
  9. UKMarine

    UKMarine Senior Member

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    Excellent, thank you very much..
     
  10. alex cnwell

    alex cnwell Senior Member

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    Your Mercedes:
    c220 w203,2004, 2014 e350 bluetec, 2004 z4 3.0 straight six
    The p1408 code i am familiar with, had this last summer on the wives w203 , with my generic code reader it pointed to the egr valve being broken/blocked, putting p1408 into google also pointed to the egr being faulty, decided to order an icarsoft mb11 and as soon as i plugged it in the culprit was clear, the dpf was blocked and could no longer generate, once i had forced a dpf regeneration the code cleared and limp mode was gone.
     
  11. OP
    Lord_Langers

    Lord_Langers Member

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    Intruiging! How does one go about forcing a DPF regen? A function of the MBII?
     
  12. m2287

    m2287 Senior Member

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    Bentley Continental GT - S55K AMG - RR vogue - Mazda6 estate
    I'm pretty sure your s class doesn't have a DPF
     
  13. alex cnwell

    alex cnwell Senior Member

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    hi, if it does not then i guess its something else, my car is a 2004 c220 with dpf.
     
  14. OP
    Lord_Langers

    Lord_Langers Member

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    Unfortunately, post 2004 S320 CDI are Euro 4, and were the first to have a DPF. Considering the p/o used it for a lot of short trips, it would be a definite possibility!
     
  15. OP
    Lord_Langers

    Lord_Langers Member

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    I'm sure that it does. The build sheet even states "particulate filter". Did you perform the DPF regen using the iCarSoft?
     
  16. alex cnwell

    alex cnwell Senior Member

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    hi mate, i unplugged the dpf sensor , it has 2 pipes attached , i used the larger diameter one and used a aerosol dpf cleaner emptied the lot down the pipe (9.00 of eBay then took the car on the motorway for an hour, it cleared it completely, its called silver hook dpf cleaner , worth a shot for 9.00. to many short runs by the previous owner i think.
     
    Taffy7hfa likes this.
  17. m2287

    m2287 Senior Member

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    Fair enough, my 2004 didn't have one luckily!
     
  18. OP
    Lord_Langers

    Lord_Langers Member

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    Well, I've bitten the bullet and ordered the iCarsoft MB II. Hopefully it gives more insight into what is causing the limp mode and EPC warning!
     
    Craiglxviii likes this.
  19. alex cnwell

    alex cnwell Senior Member

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    hi, if it does turn out to be a blocked dpf thats the tool for the job! it will also tell you the current fill state of your dpf. good luck .
     
  20. OP
    Lord_Langers

    Lord_Langers Member

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    2005 S320 CDI
    Hi again all.

    Well, the MB II turned up today, and I dutifully plugged it in and read the codes from the S Class.

    Surprisingly, none of the SIX codes in the Engine ECU had descriptions, but just "The fault code is not in the database". Disappointing - I thought this was meant to be a MB reader?!

    The codes listed are as follows;

    - 2509-001, 2527-000, 2626-000, 0100-000, 2024-000, 2025-000.

    Even more disappointingly, the MB II is unable to clear these codes. When trying to do so, the message "Fault in communication with vehicle ECU" instantly comes up, no matter what I try.

    What on earth is going on here?! :(
     

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