Brought my 2003 Vibe into dealer with CEL. The code was P0420, and after a thorough check, they replaced the catalytic convertor. So far so good, and best of all - NO CHARGE !
his first post says he took delivery on April 27, 2002, so the factory 3 year warranty has been gone by a year and a half, I'd bet the emissions warranty.I had passed the mileage on the emissions warranty when I had to replace mine. Easy enough to replace, but the part is expensive, so getting it done at no cost is great.
Good detective work ! You're right, the car is 4 1/2 yrs old, and 66K miles, so the emissions warranty covered it. The odd thing is that the O2 sensor is NOT covered past 36K miles. Had it been that, then i would have had to pay $85 for diagnosis, plus the replacement for the sensor - so i lucked out big time !