Just changed te brake pads on all 4 wheels on my 2004 E220 CDI estate. Was nervous about starting te job after Reading about the EBC brake hold function that's on this model - the one where it holds the brakes if you pulse the brake pedal. A 'Brake wear - visit workshop' message was being displayed in my centre screen in the speedometer. I bought all 4 brake pads and sensors from eBay - the seller was very helpful - Doctorcar I think was his name. The only glitch was he said I'd need 3 sensors of one type, and 1 of another, but only needed 2 of the first type (and the 2nd type). As per other postings I simply did the following- Made sure the bonnet was open Switched off the parking lift alarm (a switch under the rear view mirror) otherwise the alarm will sound when you jack the car up. Locked the car with the remote then put the key in a safe place. Disconnected the large electrical connector to the brake module on the drivers side under the bonnet- note the connector has a grab handle shape at the top that, when pulled up, will also cause the connector to self extract itself from the assembly. (The above also stops any faults being recorded on the computer, or the EBC module trying to charge itself, or pushing the brake pistons pushing out when your fingers are in the way.) Change the front pads as per any other car - 2 half inch retaining bolts to remove to allow the caliper to be moved out the way. NOTE: The passenger's side hub needs a different sensor to the other wheels - this hub's sensor cable inserts into the new brake pad half way in - I'm assuming for the 50% warning or the + symbol that's displayed with some service letters ie B+ . The rear hubs require a Torq bit to remove the caliper retaining bolts noting their heads are covered by a rubber shroud. The sensor cable is only fitted to the rear driver's side Nd is the same As the front driver's side hub. There was no sensor on the rear passenger side. Reconnected the EBC connector under the bonnet. Job done!!!