Codes read something like this....misfire, 1,2, catalyst etc etc...(don't have exact codes, but if need i can hook it up again)

had coil pack, wires and plugs replaced. Worked good for approx 3 months....Car has engine light on & blinking, smells of exhaust or some toxic fume, exhaust louder than normal and car running rough.

I am told i need a sensor............. any one know how i can tell which one? I am told my car has more than one.... any feedback would be appreicated!

Thanks
Kim

 

If you could get the codes that would be handy but, it sounds like you need the O2 sensor before the cat. There is one after the cat too. The front one is bank 1, sensor 1 on the scanner. Unless you have a dual exhaust (I don't know if an 03 Passat does) then you have 4 sensors so it could be bank 2, sensor 1. Sensor 1 helps determine the air/fuel mixture which would cause a misfire.