CLK W209 Parking Sensors overly enthusiastic

[JB052]

Mercedes CLK 280 W209 (2006)

When I select reverse the rear parking sensors appear to activate without any real justification (no obvious obstructions).

I presume there is a fault on one or more sensors, is there a simple way to test the sensors or is it a case of diagnostics such as Star or investing in iCarsoft?

I've searched the forum and although quite a lot of threads on parking sensors, I'm unable to find a simple solution.

 

[E55BOF]

An iCarsoft MB2 will tell you if any of the sensors are faulty; I don't know about any other OBD2 code readers.

An easy check would be put the car in reverse, with your foot on the brake, and have somebody cover off each sensor in turn and see if you can identify which one is over-enthusiastic; it's unlikely they all are.

 

[ALFAitalia]

Also the correctly working ones will faintly click.

 

[E55BOF]

Ah... I rather thought I recalled something about that from ages ago, but wasn't sure. OP, that's what you should check.

 

[JB052]

I couldn't hear the faint clicking sound so ended up having the system interrogated by my local independent Mercedes specialist.
There were two faulty sensors (one front and one rear) which were replaced. Sensors were expensive at over a £100 each so I didn't bother to have them painted, luckily they are black and my car is dark blue so you have to try quite hard to notice any difference.

 

[E55BOF]

HOW much...

You can get an aftermarket set of four off eBay for a quarter of that unit price. Shenzhen Specials (Chinese), admittedly, but for non-mission critical things like parking sensors I've done this quite often in the past and had no problems. I'd bet you could get genuine Bosch sensors for a lot less than OE, too.