Hi guys,

Im a new focus owner and new to this forum! I may not be a Focus owner come tomorrow. Bought a 2.0 Ford focus titanium 2 weeks ago from a garage, have had intermittant startup problems from day 1. I returned the car and it was sent to Hendy Ford (Ford main dealer) They ran it on their diagnostic equipment and it came back with 2 faults, one the HEGo sensor and also the CAT. Now unfortunatly the garage where i bought the car have offered me my money back, they sdaid that the bill from ford would be £1500 and that may not fix the startup problem. I accepted but i know i am going to miss the car and in my last desperate attempt to keep it i have a question.

Will an aftermarket air filter cause the HEGO (o2) sensor to kick up a fuss? Could this also potentially cause my startup problem? Its only done 36000 miles with a full history, it seems crazy that the CAT and sensor can be knackered so soon.

My theory is that for whatever reason the Sensor was giving wrong signal to ECU and the rich mixture has killed the Cat.

Would ford have checked to see what the air filter was doing?

I desperatly dont want to give this car back, pls help :)

Andy

Air filter would not cause that problem - the air filter is in front of the MAF so the O2 sensor would be adjusting the fuel/air mix properly no matter what kind of air filter was on it. It probably is the O2 sensor that caused the cat to fail, so replacing both should fix the problem.