Hello Dave, my name is Duncan and I also have a 2002 c220cdi estate. However, I have now covered over 277K miles in mine, and I can't truly claim that it is in lovely condition.
Sorry Dave, I have not (yet!) had any sensor problems.
In fact I had no real problems until over 200K miles.
Watch out for the rust around the rear number plate housing. It is a very weak point on that model. I took the plastic plate behind the number plate off, and was shocked by the amount of rust hidden there. If it is visible with the plate on, you have a problem that needs quick attention. I also had a bit of rust on the 4 wheel arches, but repaired it before it became visible). I am now starting to get a bit of rust around the bottom edges of the front doors.
I have had my car from new (over 10 years now) and have been very pleased with it. It still has the original exhaust, battery and clutch (it is a manual gearbox). Only major expense was refurbished injectors and front suspension bushes (210K miles) and clean out of the EGR valve and inlet manifold (270K).
Apart from that it has been mainly service items (brake discs and pads, filters and inexpensive items). This forum has been excellent for providing advice that should keep your costs down.
I plan to keep my car (if possible) while I continue to do a fairly hefty annual mileage. I don't fancy the depreciation on a newer one.