My parking sensors stopped working (long beeeeep for a while like very close to an obstacle) and then started working again, and then stopped again. The long beep eventually is replaced with a higher pitched beep (after a seemingly variable amount of time, sometimes immediately), at which point the system shuts off and doesn't come back on until you cycle the ignition.

So feeling a bit practical I took out the 3 sensors I could reach without disassembling the shield on the driver's side. For those affraid to do this yourself, they come out quite easy (assuming you don't have massive forearms and hands!); feel around the back of the sensor and you use your fingernail to lever up the top tab which is on the receptacle captive within the bumper, apply a tiny amount of pressure to the sensor to get the tab released, and then do the same for the bottom tab. The sensor then comes out, and a thin pry tool (flat screwdriver used carefully) is used to lever up another tab to remove the connector from the sensor. The cables are quite short and clipped to the back of the bumper so getting the connector off is probably the hardest bit.

One of the sensors is chocablock with water. If you shake the sensor, it leaks out of the (what I would have thought would be ultrasonically welded but obviously not) seams on the top of the sensor. See photos.

I noticed a difference between the waterlogged sensor and the other 2; the one full of water seems to be missing a black silicon type ring around the face (probably to keep water out d'oh! ). The one with the "missing" ring is actually much newer - it was fitted about a month ago by the supplying dealer as the parking sensors weren't working...!

So now I'm drying them out gently in my heat chamber and will re-fit.

Anyone know why the new sensor would be missing this ring? It looks like the key purpose for the ring is to prevent water ingress to the front face of the sensor...

I notice the stock photos of brand new sensors on the web are also missing these black silicon parts... the plot thickens.

In case water is pasing the white ring, you can also seal preventive with some silicone or Sixaflex. This will prevent that water goes into the sensors? Has anyone tried this?

Mine was also replaced last winter and now I'm much more carefull when washing the car etc. I avoid spraying water on the bumper etc.

BR,

Michael

In case water is pasing the white ring, you can also seal preventive with some silicone or Sixaflex. This will prevent that water goes into the sensors? Has anyone tried this?

Mine was also replaced last winter and now I'm much more carefull when washing the car etc. I avoid spraying water on the bumper etc.

BR,

Michael

You can actually see if the white ring is exposed or not with them fitted; just look closely for white around the sensor (between the circular clip which holds it in the bumper and the sensor face itself). Be interested to know if your new sensor is missing that ring.

It looks like the black ring perhaps performs two functions; further weather seal the sensor, and makes up the space between the sensor body and the back of the sensor clip. The sensor without that ring rattles a little in the holder as a result.

Edited 13 November, 201114 yr by jimbof

An update for those who are interested. There is indeed a separate part from the sensor - a seal ring - which needs to be fitted at the same time as the new sensor (the ones on my old sensors seem to be stuck to the sensor). The garage who fitted 2 new sensors to mine had not fitted them or transferred them from the old sensors, leaving the sensors exposed to water and rattling in the holder. Part number is 3U0919659, they were about £1.80 each for the local Skoda dealership here. Fitted in a whole 5 minutes...