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P0234 - Turbocharger Boost Pressure Regulation: Limit Exceeded (Overboost Condition)

kaz219 Aug 28, 2008

  1. kaz219

    kaz219 Active Member

    Hello again!

    Hope you guys can help me out again..

    I hired a TT Convertible and as a result, my A3 has been parked up for 3 days in my nans garage.

    Took it out and some twit in a corsa started tailgating so booted it and the revs rose and then the car went into limp mode.

    Put the car into Neutral, switched the ignition off and on and car went back to normal.

    The car was stone cold and I've never put my foot down on cold before...

    Got home and put the car on Vagcom and this is what came up:

    16618 - Boost Pressure Regulation: Limit Exceeded (Overboost Condition)
    P0234 - 000 - -
    Freeze Frame:
    RPM: 3591 /min
    Torque: 316.0 Nm
    Speed: 76.0 km/h
    Load: 91.8 %
    Voltage: 14.21 V
    Bin. Bits: 00101000
    Absolute Pres.: 2172.6 mbar
    Absolute Pres.: 2590.8 mbar
    Readiness: 0 0 0 0 0

    I cleared the fault, and took the car for a spin. I let it warm in and then drove it relatively hard (well, harder than i usually drive it when driving quick) and she was fine - No faults at all.

    First thoughts - There was a seal i didn't change when i replaced the intake manifold as i replaced it 2 weeks earlier when i cleaned it...think that might be letting air in causing the turbo to over-boost.

    2) I've not aligned the throttle body after changing it? Does anyone know how to do it - i have Vagcom.

    The car also idles abit rough sometimes when cold...

    Sorry for the lengthy post and Any help will be greatly appreciated !!

    Cheers :D
  2. RobinA3

    RobinA3 Well-Known Member

    Overboost happens when the wastegate doesn't open correctly therefore creates too much boost.

    It could be a problem with boost actuator, now i don't know how the boost actuator is feed (ie, vacuum or electronically) but if its vacuum then it could be a leaking signal pipe.
  3. kaz219

    kaz219 Active Member

    Hmm... I hope its not the boost actuator as it sounds expensive.

    I hope it's a pipe...or a leak in the pipe.

    I hope its that seal as when i didn't put the seal on, it was in limp mode all the time.

    I'm going to buy a new one and see what that does and there's also the metal gasket on the EGR which i should have changed but audi didn't have in stock!

    Thanks for clearing it up a bit :D

  4. Gti Jazz Blue

    Gti Jazz Blue Active Member VCDS Map User

    Can also be caused by sticky variable vanes in the turbo, not that I've taken a good look at the 2.0TDi turbo but I am assuming that is is a similar setup to the 1.9PD 130 / 150. These have adjustable vanes on the turbo and they can get sooted up and stick and this leads to an overboost condition.

  5. kaz219

    kaz219 Active Member

    The sticky variable sounds like what it coudl have been butt..

    I done 150miles (old trafford to bolton to liverpool to the other side of liverpool to bolton to urmston to old trafford again) and she was fine !!

    Going to put VAGCOM on it when im home so touchwood, nothing comes up!

    But for now, I'm just going to put it down to the fact the car was parked up for a few days and i didn't let it warm up... and turbo was sticky :D

    I'm going to change the seal on the IMF pipe just for piece of mind an d i hoep that sorts it as i just rented my student accomo and running skint :(

    Thanks for everyones help

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