Q: My 2000 Nissan Pathfinder was diagnosed with a knock sensor problem after a mechanic scanned the OBD2 codes. (The check engine light is on.) It did not pass the annual inspection. The car has ...

Question: I have a 2001 Nissan Pathfinder with the 3.5-liter V-6. The check-engine light came on, and I had code P0420. I was told it was a bad catalytic converter, so I went ahead and replaced it ...