Information Rear Parking Sensor fault

Techno

Member
Since buying my A2 TDi MY2001 with OEM reversing sensors it has had an intermittent fault whereby on selecting reverse the continuous warning would sound, as if you were already very close to an obstruction. Then on selecting reverse again would sometimes clear the issue, the system working perfectly, only for the fault to return...all very intermittent.

A check on the garage diagnostic showed no fault codes for the Parking system. Typically it was behaving itself when at the garage.

Looking at the information displayed on the diagnostic showed a response time (in mS) and distance (in cms) for each of the four sensors.

All information displayed was the same for three of the four sensors. The odd one out having a response time several mS longer than the rest.

The garage found a replacement sensor was rather more than £80 from Audi, too rich on a guess that it might be at fault.
However eBay had some compatible (non-OEM) sensors for less than a quarter of the price, more conducive to taking a punt at those prices.

I found replacement under this heading; OEM AUDI A2 A3 A4 A6 A8 S3 S4 S6 RS Q3 Q5 Q7 PDC PARKING REVERSE SENSOR 1PS0804G

So far so good, no failures since, the only downside is it requires painting to match the body colour.

The part number on the sensor removed is 4B0 919 275A.

Hope this helps someone.
 
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That is incredibly useful. Mine has just the same problem... How did you replace your sensor? There is a piece of trim between the bumper and the bodyshell by the boot slam panel, but I found access very difficult from there...
 
Hi Techno, can you confirm which part of the VAG COM diagnostic showed you the parking sensor response time? Cheers.
 
"Electronics 1" - 76: Park Assist. I have just fixed mine and it showed up immediately - the three good ones were around the 1.01ms mark: the faulty one was 1.48. Luckily it was one of the two middle ones, so I just had to lift the plastic trim cover between the chrome strip and the boot rubber trim and it was (just) accessible.

I can't commend this thread enough, including the part number. I paid about £23 for the genuine Audi bit and (once I'd fought the computer to get the COM ports properly configured), the job took about 25 minutes, including re-testing the sensors on VCDS.
 
Great Job! I managed to get one of the aftermarket ones for £12 and it works great, it was a corner one for me which is a shame but got my local garage to do it whilst servicing the car so not a great issue. Welcome to the world of only appropriately beepy beepers ;)
 
An old thread and I've got the sam
IMG-20220906-WA0003.jpeg


IMG-20220906-WA0001.jpeg



e problem.
Having VCDS Lite, registered, the only results I'm getting is no faults found.
 
Evening John,

If the PDC control module is showing up in VCDS then it should be ok. It may not display faults as you have pictured above. Have you tried to go through the measuring blocks as this should show the performance of the sensors and how far away an obstacle is. Sure block 001 is front and block 002 is rear. Have a go and report back your findings Sir.

It’s been a while since I played with the Rear PDC Control Module but happy to get reacquainted, laptop is on charge so I can give you a more detailed answer once I’m plugged into the car.

Kind regards,

Tom
 
Ignition on, select reverse, go and listen close-up to each sensor in turn. As a rule of thumb, a duff one won't be clicking as strongly as the others, or even at all, but that should generate a fault code. If there's nothing at all or no apparent duff sensor, it might be the control box or the wiring loom between them. A sensor fault should show up in VCDS, presumably a control box fault would also.

I have once seen the one in a set that turned out to be duff, having a stronger click than one of the 'good' ones! In that case, the error code followed the sensor as their positions were swapped (with some difficulty with the bumper in situ) by @timmus.
 
I can't even remove a fuse to shut it up.
29 - Reversing Light Switch 15A
Diagnostic Connector
Automatic Anti-Dazzle Interior Mirror
Navigation System with CD Drive Control Unit
Parking Aid Control Unit.
 
I can't even remove a fuse to shut it up.
29 - Reversing Light Switch 15A
Diagnostic Connector
Automatic Anti-Dazzle Interior Mirror
Navigation System with CD Drive Control Unit
Parking Aid Control Unit.
Evening John,

Have you checked the codes on the sticker to see if Rear PDC was a factory fit or retrofit. If it’s a retrofit then it’s possible that the fused feed isn’t as per the production line and it’s been taken from elsewhere within the vehicles harness.

This is can be an issue when something goes wrong and you need a quick fix until a full repair is possible. I know when I do this particular retrofit in 250 that I’ll be taking it back to the correct fuse under the steering column as I have other work to do in that area at the same time.

Did you manage to test the sensors within the measuring blocks or the clicking sound test that Ian suggested.

Kind regards,

Tom
 
I've not had chance today Tom, they are original.
Going to have a go tomorrow
John,

If it’s factory fit then removing the fuse must cut the power supply to the PDC control module. Are you certain that you’re removing the correct fuse. Depending on the revision of the fuse layout sticker then you might have to turn it upside down so the sticker correlates to the actual fuse arrangement.

Kind regards,

Tom
 
John,

Just checked the fuse layout for you:

15F2C82E-2DBC-44C7-B397-87359872B373.jpeg


image.jpg


Fuse 29 is for the reverse light. Try fuse 37 as this is the factory feed for PDC. Removing this would also cut power to the factory navigation but think you have a RNS-E retrofitted so it should continue to function with fuse 37 removed.

Kind regards,

Tom
 
I can't even remove a fuse to shut it up.
29 - Reversing Light Switch 15A
Diagnostic Connector
Automatic Anti-Dazzle Interior Mirror
Navigation System with CD Drive Control Unit
Parking Aid Control Unit.
Mine is fuse 37.if that's helpful. removed it 3 weeks ago. Also added decibel app on iphone as well to try to find issue but not found so removed fuse. Hope that helps. Tones.
 
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