W204 Parking Sensors Faulty (Help/Ideas please!)

[moj91]

Good evening all!

After a recent bout of rain, the W204 has developed a problem with its front parking sensors, I assume one or more has gotten wet.

Is this common? Is it usually the sensor(s) or could it be a loom connector fault? Is there anything i can do to the okay ones to seal them from also failing from water ingress?

Can diagnostics tell which sensor it is, or do i have to have them all replaced?

Is it something i can repair by myself by trial and error? If so can anyone point me towards a reputable supplier for the part without having to pay dealer prices?

Any thoughts/input appreciated! Thanks!!

 

[whitenemesis]

Fairly common fault, nothing one can do to forestall it. STAR/XENTRY can pinpoint the failed sensor. IIRC about £50 from MB. You may need to remove the bumper to gain access.

 

[moj91]

Is it worth me trying to find a local person with Star to pinpoint the failed sensor and replace myself? Are they hard to do? Do any fault codes need clearing before the sensor/PDC will come back to life does anyone know?

 

[whitenemesis]

Yes, a good indie will have no probs identifying the culprit. Easy to remove and replace, simply plug and play. Access might be restricted and require bumper removal, depending on sensor location. No reset required.

 

[moj91]

Thats great, thanks!

 

[moj91]

Ran diagnostics on it and its not showing any faults... still the same symptoms. I'll reply again if/when we find out what's causing it!

 

[whitenemesis]

What are the symptoms?

 

[television]

Ran diagnostics on it and its not showing any faults... still the same symptoms. I'll reply again if/when we find out what's causing it!

On STAR or other.

 

[moj91]

On STAR... haven't had time to look at it again/get it into the garage recently. I think its just one front offside sensor. I've gotten into a good habit of turning the sensors off as soon as i start the car now haha!

Car gives the LED signal/beeper signal that it would give on the front offside if i was parked up against something. Rears are fine and work. occasionally i get all the sensor displays reading just two red led's and a different solid tone, which i guess is the system's default 'im broken' display...

Only thing that has come to mind is that i screwed a new front numberplate on a few months back, although i had the grille out and pryed the bumper forward to watch where said screws went, so as to not catch any wires etc. i guess there is a chance i missed one or a cable has started rubbing on a screw.... who knows without popping the bumper off...

 

[moj91]

Sorry to bring this back up, but i seem to have found my solution, which is worth sharing with others!

Turns out that in my case it is not down to a faulty sensor, or damaged wiring, but the numberplate holder. The one I had on before had split a clip, causing one side to stick out fractionally further than the other side (3mm max maybe?) Which it seems meant that it either protruded (just) into the zone of a sensor, thus triggering the odd 'fault'. I replaced said holder with a new dealer one (bar 2mm, the same depth) and the problem was solved!

 

[whitenemesis]

Well done!

It's actually mentioned in the WIS documentation on the PTS system. Advising dealers to check the front plate holder and if an aftermarket frame is fitted.

Something for us to keep in mind in future.

 

[moj91]

I was amazed that such a small protrusion was the culprit!

I had never checked WIS for this issue... guess I could have saved a lot of aggro if i had!

The odd thing was that i changed the holder, it then was fitted (with said clip broken) for a while before the issue cropped up.

 

[imspringcleaning]

Thanks moj91, I had exactly the same issue... Just a bit of tightening the number plate sorted it. Super!!!

 

[markg14]

Sorry to bring this back up, but i seem to have found my solution, which is worth sharing with others!

Turns out that in my case it is not down to a faulty sensor, or damaged wiring, but the numberplate holder. The one I had on before had split a clip, causing one side to stick out fractionally further than the other side (3mm max maybe?) Which it seems meant that it either protruded (just) into the zone of a sensor, thus triggering the odd 'fault'. I replaced said holder with a new dealer one (bar 2mm, the same depth) and the problem was solved!

I had this myself when the self-adhesive sticker on one side got wet, and the numberplate stuck out a bit more than normal....

 

[andreiIN]

Hello everybody,

I know this is an ancient topic. But I am having some problems with the front (right) sensors as well.
I was hit by a Land Rover with a towing hook. The damage was done only to the number plate and the guys from the service changed it.
Since then the right sensors are going mad. In ~75% of cases I break in traffic, the front right sensors go off.

I have attached some photos of the new number plate. Do you see anything suspicious here?
My guess is that either the number plates are not well installed, or the sensors are not well installed back (because the front bumper was taken down in service for the accident report).

Thanks