Parking Aid Sensors & WD40 - explain it to me.

[Scarletpimpofnel]

I've a Jaguar XF daily with 8 parking sensors and a rear view camera. Stopped working last week in the dry albeit after on / off rain for a week or two.

Essentially when any component of the system fails the whole system fails to work which is annoying! So a single sensor fails and camera and other sensors stop working too.

Anyway much Googling suggested all sorts of stuff from wiring looms, fuses, sensors etc. My £10 OBR reader showed no fault codes (there will be some but not visible to my cheap pos OBR reader).

Anyway whilst expecting an expensive dealer trip I saw a comment online about cleaning the sensors, did that (they are always clean anyway) but no luck. Then saw another comment about squirting the sensors with WD40. To my surprise that worked.

I believe these are ultrasonic sensors so how does WD40 fix the issue? Does the round central part of the detector actually move within the ring that surrounds it so WD40 cleans/lubricates that gap? I have no idea: Why did WD40 fix my issue? Thanks.

OT: I had no idea how bad I am at parking without these driver aids that I have become used to, so glad to have it back.

[GeniusOfLove]

Clue is in the name WD - Water Displacement.

Water seems to be what knobs these up, although having replaced loads I'm not sure how it gets inside but there is a definite correlation particularly with the FoMoCo ones I bet your XF is still using (like all Jaguars for 30 years).

It is a knob that one duff sensor means it kills the lot, my XK has a dead sensor at the front left so I get no rear parking sensors either.

[RSTurboPaul]

GeniusOfLove said:

Clue is in the name WD - Water Displacement.

I never knew that!

[Dog Biscuit]

RSTurboPaul said:

GeniusOfLove said:

Clue is in the name WD - Water Displacement.

I never knew that!

And the 40 means it was the 40th incarnation of it that made the current product and that went to market

[Scarletpimpofnel]

GeniusOfLove said:

Clue is in the name WD - Water Displacement.

Water seems to be what knobs these up, although having replaced loads I'm not sure how it gets inside but there is a definite correlation particularly with the FoMoCo ones I bet your XF is still using (like all Jaguars for 30 years).

It is a knob that one duff sensor means it kills the lot, my XK has a dead sensor at the front left so I get no rear parking sensors either.

Thanks. Yeah I get what WD stands for hence mentioning the wet weather. But I thought the sensors were like a sealed unit and I only sprayed the WD on the outside circular bit that is viewable in the bumper after it had been dry for a few days. So if sealed why did WD40 work? Does the front move and had that seized up? I'm trying to understand what the issue was that WD40 fixed.

[Krikkit]

Get a decent code reader on it and find out which sensor is diff, then replace

Or process of elimination with WD40 until you find the one

[GeniusOfLove]

They look pretty sealed when you change them. I've wondered if it's the rubber isolation ring between sensor and bumper that gets bothered by water rather than the units themselves.

[uktrailmonster]

Scarletpimpofnel said:

Thanks. Yeah I get what WD stands for hence mentioning the wet weather. But I thought the sensors were like a sealed unit and I only sprayed the WD on the outside circular bit that is viewable in the bumper after it had been dry for a few days. So if sealed why did WD40 work? Does the front move and had that seized up? I'm trying to understand what the issue was that WD40 fixed.

Nothing moves in these sensors.

[Robertb]

Dog Biscuit said:

And the 40 means it was the 40th incarnation of it that made the current product and that went to market

The tragedy is that the guy who started developing it got to incarnation 39 before he gave up and sold his idea.

[frisbee]

If you run your finger over the sensors when they are on you can feel if they are working.

The idea of one bad sensor causing the system to constantly report an imminent impact is sound, if it just ignored the duff one old duffers and duffesses would be reversing out of the 5th story of multi-storey carparks constantly.

[Dog Biscuit]

Robertb said:

Dog Biscuit said:

And the 40 means it was the 40th incarnation of it that made the current product and that went to market

The tragedy is that the guy who started developing it got to incarnation 39 before he gave up and sold his idea.

Really? Oh no that must be gutting!

[eliot]

frisbee said:

If you run your finger over the sensors when they are on you can feel if they are working.
.

or put your ear right next to it and you will hear it clicking.
on my e39 the diagnostics were never able to tell me anything about which sensor had the problem - so i used my ear.

[Belle427]

Check for water on the actual electrical plugs but they are a sealed item.

[Scarletpimpofnel]

Krikkit said:

Get a decent code reader on it and find out which sensor is diff, then replace

Or process of elimination with WD40 until you find the one

I’d love a decent code reader but can’t afford it.

Good idea about trying one sensor at a time. I’ll try that if it happens again. It’s a right daft to change, the whole bumper has to come off.

[njw1]

What year XF is that? I ask as my '08 XF has a knackered sensor (right rear inner!) which has obviously knocked them all out but I haven't bothered sorting it as the screen still works on my car.