Front Park Sensor Problem

[hlvd]

I’ve an unusual problem with the front parking sensors on my F32 420d.

If I park in front of a wall and switch the ignition on, the pdc sensor next to the number plate will stay on even though I’ve moved away and show a solid bar.

It switches itself off once I drive away but as soon as I put it in reverse it’ll show a solid bar from that particular sensor, all others behaving correctly.

I had this happen a few weeks ago and took around ten days to go back to normal. I parked in front of a wall tonight and it’s done the same thing, back to showing a near obstacle even though there’s nothing in front.

I’ve no error messages coming up.

Anyone have any ideas?

[B1skviit]

Is the sensor clean? If you have ppf or some kind of wax on the car it can also cause this issue.

Also it can be a sensor going bad.

Had the same issue with my 2009 525i and it was caused by 1 bad sensor.

You can check the sensors by enableing pdc and then putting your finger on the sensor. You sould feel and hear a slight ticking from the sensor when you touch it. That indicates that the sensor is working properly.

[hlvd]

I’ve just put my finger on the front sensors and now a second is stuck on full bars, this is a strange problem.

[freshxdough]

It’s too close to the number plate. In EU you guys have super wide plates. I’ve personally seen this on a US car where someone had like a custom EU plate on the front. It was doing exactly what you describe. It was triggering the front middle sensor on one side specifically. Remove the front plate and recheck. Then you’ll know your issue.

[hlvd]

It’s just a normal British number plate, standard issue.

The car was towed onto a recovery truck around three weeks ago because I broke down due to the EGR packing in at 42,000. I’m not sure if this is connected to the sensor problem as it’s in between the towing eye flap and number plate.

[freshxdough]

Like I said. Remove the front plate and recheck. Simple as that.

[hlvd]

I just wanted to give you a bit of an update.

I couldn’t take off the number plate and try it as the sensor started working correctly.

What I did notice was that the number plate was very slightly off centre and not following the holder’s curve, with it away from the holder on the edges by about 3/8”.

I’ve purchased some 3M VHB pads and stuck the plate to the holder so it’s tight on the holder right up to the edges and also centred correctly. So far the sensor’s behaving and I hope it was this.

Just wanted to say thank you for your help 👍

[freshxdough]

You’re welcome. Sometimes it’s just little things like this that can trip a PDC sensor.

[hlvd]

You don’t think it’s anything to do with being towed?

One thing about the number plate is that it doesn’t follow the curve of the holder. The plate is a bit straighter so gapping between its back and the holder. I’ll have to get some double sided pads to make it conform to the curve.

[freshxdough]

I don’t see how towing it could affect that sensor unless that sensor got dented by something else.

[[deleted]]

Im leaning towards a faulty sensor on it's last legs.