Originally posted by TXBill
I thought you had one for each pad up front, that's how my old W123 and W126 cars were, so you needed two per side, 4 total. No, of course the rears have no sensors.
EDIT: The following page on the E class brake pad change shows two sensors on one caliper, so that would mean that to do both front wheels you'd need four sensors total.
Yes the E420 has the two sensor caliper. But my car and a lot of the earlier W124's have the single sensor floating caliper. Thats why I want him to double check, its any easy mistake to make thats all