Interactive wiring reference for the GM E67 ECM as fitted to the 2008–2009 Chevrolet Trailblazer 4.2L Atlas I6 (LL8). Built for a '54 Chevy LL8 swap, but applies to any project that uses this ECM.
P0420 is a well-recognized error code within the automotive industry, notorious for its persistence. Luckily, this article is designed to guide you through ...