DTC P0420: Catalyst System Efficiency Below Threshold: Notes

NOTE: Heated oxygen sensor for cylinders No. 1 and 4 is referred to as bank No. 1 sensor No. 1 and is located at timing chain of exhaust manifold above catalytic converter. Heated oxygen sensor for cylinders No. 2 and 3 is referred to as bank No. 2 sensor No. 1 and is located at flywheel end of exhaust manifold, above catalytic converter.

NOTE: For component location, see appropriate illustration in THEORY & OPERATION article.