Rear parking sensors - strangle fault, help appreciated!

[GE90]

Hi All

Sorry, but would really appreciate some help. I have a 2005 A4 Avant. The rear parking sensors have been intermittently playing up for months. They sometime don't come on until too close, but main problem is that I SOMETIMES get a constant warning after selecting reverse without reason. If I restart the car it seems to reset and work....

Right, there are no fault codes according to main dealer (£110 later!). I have replaced all sensors with eBay ones from Bob Audi, advertised as genuine OEM (maybe not...?). I have replaced the controller with a new one I purchased from Audi (£120!), and have removed and inspected the harness. However, problem is still present!!!!

Any ideas appreciated, driving me mad!!!

Thanks

[kblackburn]

Hi, I have the same problem with my Seat exeo (A4) b7, been to the dealer several times, with the same result as yourself. However, I had vcds and it clearly shows faulty sensors, intermittently, so this last time I recorded it on my mobile to prove the fault, success 2 faulty sensors under warranty. You need your car on vcds in measuring blocks, and just watch the sensor activity.

[TommyTits]

Have the sensors and feeds been checked? I've worked on cars where the sensor or sensors have been the problem themselves...example....moisture finding its way in, also the wiring has chafed on something causing a short etc. A down sensor can confuse it to buggery...just a thought

[GE90]

Hi TT, thanks for your reply. These have already been checked by Audi, and typically enough they worked perfectly while at the dealer. Drove home, parked on the drive - constant tone!!!! Just don't know what to do next.....?

[kodkod.84]

The £110 'scan' charge is diabolical- VW tried charging me this for an ESP fault on the MK5. You can get a decent scanner for less than this. Bet they still charge for this even if you go in with a print out of the fault codes...

[GE90]

Yep, agreed!! Any ideas??????

[Doctle Odd]

Plug it into VCDS and take a drive, gather some live data it should pick up intermittent faults VWAF User Location Map - VCDS - Google Maps

[TommyTits]

Have you a tow bar??? Man or auto??? aftermarket of factory fitted??? factory im guessing...erm its a hard one indeed as you have check or replaced everything that you can to do with that area.

[TommyTits]

Tip...You should hear a fast clicking/crackling from sensors if they are doing their job, ignition on engine off, in reverse, hop out and have a listen...I am with Doctle odd too, Hooked up roadtest would be good but more expense...normally 2 types of faults shown, intermittent or permanent, if intermittent quite possible that they are clearing themselves, very likely that the sensors will have an intermittent rather than a permanent.

[GE90]

Thanks.... No tow bar, manual and factory fit........ No sound, but I can feel a tapping type sensation from each of them. Perhaps dodgy ebay sensors then? I would be a little surprised, as seller has good feedback and sold lots of them over a few years! I suppose it can only be the sensors or the harness....??? Thanks again