I've owned a 2000 C70 for 1.5 years and have a recurring, intermittent problem with the convertible top sensor. About 25-33% of the time after starting the engine, the convertible top warning light goes on. When you start driving, it "dings" incessantly. The only way to stop the ding warning is to stop the car, engage the parking brake, and press the convertible top button. The top opens partially, then returns to closed position. It's quite inconvenient especially in the rain.
I've had two mechanics look at this, one was dumbfounded, and the other said the electronic sensor needed to be adjusted by a Volvo dealer that has the proper computer equipment. Two dealers have not been able to fix the problem.
If anyone else knows about this problem and a solution, please share.
Karen