P0420 Buick -

Question

The cat. converter has been replace twice on my 2002 Buick Century but I continue to get code P0420 after the vehicle has been driven appx. 2,000 miles.. No other codes appear. Both O2 sensors have also been replaced. What do I need to do next?

Answer 1

Hi there,

If the engine isn't burning clean it can cause issues with the converter. I would consider a tune up and checking to make sure you don't have a leaking fuel injector. It's also common to have an exhaust leak cause this type of issue as well.