I have a 2002 astra 1.6, and 2 weeks ago the emissions light came on. I took it to a local garage and they carried out a diagnostic on it, and it came up with the fault code of P0420, which relates to the cat, or the H052 sensor?
They tested, and both the sensors were working fine, they also put the car through a emissions test and it passed fine, so they reset the light on the dash and it was sorted, but friday just gone, I had been out for a drive with a friend and it came back on again
The mechanic said that there could be carbon getting on the ends of the sensors? If thats not the case has anyone ever had this problem and could point out what it is?