New Pad Thickness E320 CDI
 

Does anyone happen to know the thickness of OEM brake pads (MB branded) front and rear for a 2006 E320 CDI? Dealer says rears are "about half an inch"....so much for German precision! ;) My rears are original at 153k miles and are at about 4mm. Just trying to gauge how many miles left (assuming similar driving habits).

Just replace pads. 4mm is low. They are normally 8-12mm thick. Why skimp on the most important part of the car.

An indicator light will come on when it is time to replace them.

What happens if the warning light does not work? Too late when you hear scraping sound against the rotor. If the OP makes an effort to inspect it, presumably removing the wheel, and concern about the thickness then just replace them. Personally, I do not wait for the light to come on. I change them after 20K to 25K. Pads are cheap if you do it yourself.

Or you can test the warning circuit by shorting the sensor to chassis. The light should come on. I do it when I change the pads.

Wear indicators trip at about 3mm so I have no concerns about 4mm.

Also note that the wear indicators will only trip once or twice, after that they are just rubbed away and no light appears.

Happened to my W124 - wife told me later she saw the lamp light up twice in a day - as it was yellow and not red, she didnt bother telling me.

a month later she wore the pads into the rotors.

In the car mentioned by the OP the light will stay on. The sensor is a wire loop that triggers the warning if grounded or worn to the point of an open circuit of the loop. The main problem is that there is only one sensor per axle and if a pad wears faster than others you could ruin a rotor without a warning.

I agree, just replace them. 4mm is worn pretty well. You want to replace them BEFORE rivets start wearing through the friction face.