Hi everyone. forum n00b here with a couple questions.
car:00 ES 5spd 1.8L 118k
Last night my ses popped on. Pulled P0421 for warmup catalyst effeciency. Alldata lists possible causes as (WU-TWC) <---(first main cat), exhaust leak, loose front or rear 02s, or bad front o2. im leaning towards...