Kessy system working sporadically

Discussion in 'C6 platform' started by Carrera-GTI, Dec 9, 2012.

  1. Carrera-GTI New Member

    Hello, I have a 2005 Audi A6 Avant with factory fitted Kessy / Keyless system.
    The system has never quite worked reliably (I purchased the car second hand).
    Doors: I have to be very patient to open the doors (and sometimes doesn't work or I'm not patient enough). Same goes for locking the doors with the black rubber button on the handles.
    Engine start/stop: Sometimes never works (or inpatient) and sometimes I get "no key identified" and other times it just works. However, I notice that if I have managed to start the engine with Kessy I can always Stop engine with Kessy.
    Further information:
    VCDS: I have scanned the car and have no fault codes.
    Weather: I have noticed that now it is cold Dec the system has started to work much much better.
    Observations: While cold weather and system seems much better I can open and lock easily well from all doors (and start/stop engine from within car).
    Battery: Is brand new, original Audi and coded to the car.
    Software: Audi Specialists checked and there were no software updates for my car for this system.

    What could be the problem? The Kessy unit? Antennas? Anything else? I am very puzzled as to what this could be so would be grateful for advice as handing it over to Audi blindfolded is just not an option as too expensive.
    Any advice from your experience would be MUCH appreciated.

    PS: I have read the Kessy unit sometimes need refurbishment as two Mosfets on the board get tired with age but not sure if the symptoms of my car fit this approach?
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  3. peri77 Member

    Check the measured values with VCDS in 05 - Access/Start auth. module MWB 2 :

    Measured value block 2: Entry and start authorisation button -E408
    1. ON button (on/off)
    2. START button (on/off)
    3. STOP1 button (on/off) *see also measured value 131
    4. Touch sensor (Bit 7-4: not used; Bit 3: RR; Bit 2: FR; Bit 1: RL; Bit 0: FL)
    '0 0 0 0 0 0 0 0'
    Bit 7 ...<--... Bit 0
  4. thedenz0 New Member

    I have a similar problem. You may want to check your battery in your remote and in the car. I know you said it was replaced but it doesnt hurt to double check.
  5. Carrera-GTI New Member

    Hi peri77,

    Since my last post I have had my Kessy unit looked through and tested by professional auto electronic company and nothing wrong was found (MOFSET and transistors were fine).
    So, I would like to try to measure values as you suggest as I assume this would allow me to see if a value is off and this pin-point the root of my problems?
    I should be able to go through and read these values but what should I do with these please? What would be the correct values to have etc?

    Many thanks
  6. peri77 Member

    As you said all functions of the system (opening, closing, starting the car) sporadic, I would suspect some "central" part of the system. Try to replace the kessy unit. Its under the glovebox. You can find cheap units on ebay.

    This is what I would try the first...

  7. Carrera-GTI New Member

    Thanks peri77,

    However my kessy unit (from under the glove box) has just been checked and is working fine (MOSFET's and transistors checked) though it could of course be something else than the MOSFET's or transistors?

    I can buy a new kessy unit cheaply second hand on eBay but as it would need to be paired by Audi as far as I understand it will be a costly affair to try out.

    Preferably I would like to try to diagnose and pinpoint the problem before to avoid changing out too many parts that might be working.


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