Question

P0420 Code keeps coming up on my 2001 Chevrolet Impala 3.4L, help please

Answer 1

Hi there,

The P0420 code is for the catalytic converter, while the P0171 is for a lean running condition on bank 1. I would check for intake manifold leaks and the front O2 sensor. If either has an issue it can cause the lean fuel mixture, which in turn may result in the catalytic converter code appearing.

Answer 2

P0420 CHEVROLET - Catalyst System Low Efficiency Bank 1
Read more: https://www.autocodes.com/p0420_chevrolet.html