Question

2005 Cadillac CTS 2.8L with check engine code P0420, please provide repair recommendation

Answer 1

Hi Paul,

Quite honestly in most cases when I see this code it's going to need the bank 1 converter to solve the probem. However, sometimes the rear O2 sensor can cause this code to come up. It really should be diagnosed propery to make sure the correct repair is made to resolve the issue.

Answer 2

P0420 CADILLAC Code - Catalyst System Low Efficiency Bank 1

Read more: https://www.autocodes.com/p0420_cadillac.html