Code p0420
Hello. P0420 (https://www.yourmechanic.com/article/p0420-obd-ii-trouble-code-catalyst-system-efficiency-below-threshold-bank-1-by-jamahl-walker) could be due to a variety of faults including even a fuel pump that is not supplying sufficient fuel, causing a lean condition, and hence "fooling" the O2 sensors (pre and post) as to the status (i.e.,...