P0420 is a pre-cat code for bank 1. if that is the only code that you have. if you have a p0420 and any other bank 1 O2 sensor code then it could be a false P0420.
chances are the pre-cat is fine but it could be shot and when that happens and it has degraded enough it will effect performance.
you have the following options
new pre-cats from the dealler - $$$$$$$$$$$$$$
MSDS headers, etc - $$$
mil-eliminators - $
you can also gut the pre-cats too ...
chances are the pre-cat is fine but it could be shot and when that happens and it has degraded enough it will effect performance.
you have the following options
new pre-cats from the dealler - $$$$$$$$$$$$$$
MSDS headers, etc - $$$
mil-eliminators - $
you can also gut the pre-cats too ...