About 40 miles before my 2.2HDi 406 estate turned 100,000 miles the engine warning light came on. The error code that caused this is P00C2 (Thats Papa Zero Zero Charlie Two) which according to all sources is a invalid code. If this code is reset whilst the engine is above about 40 degrees the code does not return until the engine is next started from cold. I removed the connector from the collant sensor, reset the code and it did not reappear. Changed the sensor, fault code still active. This code appears to have no effect on the performance of the car whats so ever. Does anybody have any idea what causing it please.