Q: I have a 2009 Pontiac G3 with a 1.6-liter engine. The “check engine” light came on about six months ago showing a P0420 catalytic converter efficiency code. Since then I have replaced both oxygen ...

with the 4.0-liter six-cylinder and about 120,000 miles. I keep getting a catalytic converter code P0420. I heard there may be a way to fix it by spacing the O2 sensor away from the cat and changing ...

Thanks to modern fuel injection, the engine computer has extremely precise control over the proportions of the air/fuel mixture inside the cylinders. A countless number of sensors around the car tell ...

Q: I have a 2010 Honda CR-V. Last month its check engine light came on. I'm a retired mechanic and my scanner found code P0420 — catalytic converter efficiency. I tried a catalytic converter cleaner.

My 2005 Nissan Altima's "Service Engine Soon" light has turned on twice in the past month. A diagnostic test indicates that my catalytic converter is "failing". If I don't have the converter replaced ...

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 ...