UK-POLOS.NET - THE VW Polo Forum

Driving in the rain yesterday I had Error:front ParkPilot pop up on my MFD accompanied by the ParkPilot button flashing yellow whenever I was under 10mph which is when I assume they activate automatically.

I plugged it in when I got home and got the fault, Front RIght Parking Aid Sensor: Open or short to ground.

I took out the drivers side headlight and could see that the sensor was still plugged in and didn't feel loose. Banging on the bumper did get the error to go away and it would sometimes come back. So I'm assuming there's a loose connection somewhere in the harness or its rubbed through and water is getting to it.

Banging anywhere on the bumper got the fault to go and after sitting for a couple of hours the fault was gone entirely. Drove again in the rain, and the fault returned. Let it sit overnight the fault has gone.

Are there any known spots that the harness could rub through and or let water in? Is it possible to test the sensors with VCDS?

Also which sensor would be the front right? The furthest right under the headlight or the one between the number plate and the headlight?

A fully VW Group compliant scan tool should be able to identify which parking sensor was failing, ie distinguish between inner and outer right sensors.

Other way round this would be to swop the right outer and left outer and see if the fault moved, same for the inner right and left, if none of that "moved" the fault, then now you would know that it is a connector or cabling problem.

Eventually if you remove the complete bumper, you could check the continuity of the cabling main connector to each sensor as each sensor gets a +12V DC, OV and O/P, the +12V DC and 0V are commoned together.

Would it be possible to meter out the harness from the main grey plug that's on the passenger side of the bumper in the engine bay?

Seems like It'll be quite the faff to get the bumper off with PDC sensors and headlight washers. I might get more access by taking out the foglights and upper grille as the telescopic part of the headlight washer stops me from getting good access to the sensor.

After a quick bit of digging on google, seems VCDS identifies the sensors as front left, front left center, front right center, and front right. So it seems my issue lies with the one under the drivers side headlight whether it's the sensor or wiring.

After giving it some time, it seems the short is caused by water ingress into the sensor. I've only had the fault return once in 10 days and it went away in the same drive within 5 minutes. Access to the sensor with the bumper still on the car is very limited so I think I'm just going to see if the issue happens more frequently before I decide to have a good go at sorting it.

I managed to shove my phone in the gap created by removing the headlight and saw that the sensor itself was quite wet compared to the rest of the inside of the bumper. As well as a place that looked like the wiring was in contact with the bumper without any protective sheath and could be susceptible to rubbing through.

For now, I've blown off the sensor with compressed air from the inside and outside of the bumper to try and get any trapped water out that may have gotten through the seal between the sensor and the bumper.

Do you think that with the info these pictures have given you that you could remove that parking sensor, as you can see, the sensor is clipped into the mounting bracket at 2 points, so easing these clips up a bit and then applying a bit of pressure from the front of that sensor should allow it to come out of the bumper skin, I'd think that the connector just needs that white tang pulled back and then you could pull that connector off.

Edit:- the unprotected short section of the wiring will be normal and I'd doubt if there was much if any relative movement taking place.

Could be possible just depends on how much pressure is needed to open the clips to get the sensor out as I'm only able to get one hand in. Also doesn't help that I won't be able to see what I'm doing.

Annoyingly removing the fog light didn't really do anything for access or visibility as the bumper support/headlight bracket (visible in pic 2) makes it impossible to reach it from underneath.

I'd think that one option is to buy a copy of the official workshop manual, I bought mine from "easymanuals" - for both of our cars, I've already taken the front bumper cover off my 2011 Audi S4, I had to as I was determined to retrofit front parking sensors as per what the factory would have done.

I've also taken the front bumper off my wife's previous 2002 Polo.