R171 rain sensor advice

Neilr171 said:

I could do with some clarification as to whether I can retrofit a light/rain sensor
to my SLK 200 R171 2006.
Question 1
Would the wiring already be within the loom ?
Question 2
What would be the correct sensor to fit ? ( There appears to be several different part numbers to choose from )
Question 3
Is it practical to fit a used one ? (I assume it would require a new silicone pad and if so are these sold separately ?) Should that be Question 3A or 4 ?
The sensor currently fitted to my car is Part No A171 820 45 26.
Would Part No A171 820 15 26 be the correct replacement ?
And finally I assume my local UK MB dealer would be the only place to buy new from, or is it ?
PS.
I know I'd have to wish upon a "Star" to enable it.

Happy Christmas you animals !
:bananapartyhat:

Click to expand...

Craige's suggestion on reading the linked thread should answer most of your questions. But since you asked about specific part numbers - you are probably correct in what you currently have. The sensors have been superseded over the years and the latest part number for the combined light and rain sensor is 171 820 54 26.

You can sometimes find used ones on ebay or from a junk yard/dismantler/breaker, but they will not likely be the latest version. If you call a junk yard they will likely not know if the SLK on there lot has the sensor or not. The best way to determine that is to pull the data card for that car's VIN and see if it has the 345 Rain Sensor option listed.

My online OEM MB parts sources show a cost of about $53 for the sensor so sourcing a used one may not be worth a lot of effort. New gel is needed and is discussed in that other thread.