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Thread: Audi Q7 4.2 FSI CRANK BUT NO START PO685

  1. #1

    Angry Audi Q7 4.2 FSI CRANK BUT NO START PO685

    Hey guys looking for suggestions for my Q7, car has been at the mechanics for close to 3 months.

    We went away for a getaway when we ran into a huge storm. The following day we got into the car to drive away and when the car was started we had a number of dash lights ESP ABS TRAC lights all turned on. We stopped the car cycled the ignition and all went away. Drove about 100mt down the road and the car stopped dead. Cranked but not starting.

    Car got towed the mechanic, mechanic was under the impression it was a water damaged ECU. Fuel is not reaching the engine, no power at fuel pump. ECU was sent away along with all the related components. ECU came back as no fault found. There was an engine code on the computer PO685. Mechanic said that all analysis off the ECU pointed to a water damaged fuel control module stop fuel control modules replace with a new one still no start, all fuses and relays and solenoids have been checked still no start, fuel pump has been replaced still no start. Any suggestions any comments will be much appreciated thank you. I'm having the vehicle picked up from that mechanic and taken to another mechanic that works alongside and order electrician has anybody heard of an issue like this in the past, vehicle has a new battery.

  2. #2
    Join Date
    Dec 2013
    Thanked: 278


    Have a look at this. Do you have any other fault codes at all. Water, maybe, static charge possible too. What ever way you're getting the usual change it and try rather than a bit of knowledge applied. Good luck. This fault code diagnosis should apply across the VAG range but there may always be exceptions.

    17069/P0685 - ECM Power Relay Control Circuit (J271): Open Circuit

    Possible Symptoms

    • Malfunction Indicator Light (MIL) ON
    • Engine doesn't start

    Possible Causes

    • Voltage supply issue for ECM
    • Faulty ECM Relay (J271)

    Possible Solutions

    • Test voltage supply to ECM
      • Check wiring and fuses

    • Replace Faulty ECM Relay (J271)

    Special Notes

    • When found in a 2005 through 2007 2.5L NAR (North American Region) (1K) Jetta check the T121/62 (Red/Black) traced power wire to the ECM. If power is missing or a voltage drop is present that wire may be damaged anywhere between 6" and 18" from the connector itself. This will result in no communication in addition to a no-start.

    • When found in a Canadian Market (1J) chassis City Golf using engine code BEV, make sure that the B474 splice which powers T121a/62 (Red/Green) traced power wire to the ECM isn't corroded.
    Last edited by IchBautAuto; November 7th, 2021 at 04:51 PM.
    C5 RS6: Sportec, Milltek & Wagner -- B5 RS4 : tastefully modified -- Audi 1.8 quattro 132 Kw -- UNIMOG 404 TLF8

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