Just got an 02 Yukon and have a few questions.
1. Got the following codes: PO420, B0434, P0442, what are they and how do I about fixing them?
2. What mods are recommended for reliability, performance, and mileage?
Thanks,
Corey
2007 Chevy Classic CCSB LS 4x4 w/ LBZ & 6 Spd Ally
Greystone...