Electrics: Parking sensor fault (3 & 6)

[Arianne]

Can anyone help?

Since we've owned our XC90 (from new in 2006) we've spent a fair bit with our dealer periodically having parking sensors replaced.

Our car is pre-face lift which means that the bumpers are not painted but grey plastic. We regularly apply Mer Bumper Trim Gel to keep them looking nice but we wonder whether this might be causing the sensors to fail?

The dealer recently diagnosed the problem being with sensors 3 & 6. They told us one was on the front and the other at the rear - so the cost would be big because both bumpers must be removed to access and replace the individual sensors.

I would like to try cleaning the sensors with a toothpick and WD40. I've read about this elsewhere. Is it wise to do this?

Which sensors are 3 & 6?

Is there anything I can do myself to fix these little critters? I have a garage and would be prepared to spend some time on it. But how complex is it, do I really have to remove the bumpers and where does one get the parts / know the part numbers?

Finally, now that the dash lights up with the 'Park Service Required' warning does this mean that nothing will work, even if I clean them and it rectifies the issue, until the dealer resets the fault codes etc?

To be honest, the prospect of continually spending £££ on these sensors every 12-18mths is annoying. But the warning message is eating away at us every time we start the car and, whenever we try and reverse parallel park in our local town centre, one of us has to get out to guide us in!

Help..........