DTC Advanced Diagnostics: P0420: General Description

Courtesy of HONDA, U.S.A., INC.

The three way catalytic converter (TWC) is monitored by the signals of rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) and rear secondary heated oxygen sensor (secondary HO2S (bank 1, sensor 2)). The powertrain control module (PCM) calculates the sum of the absolute differences of the rear A/F sensor (bank 1, sensor 1) signals at regular intervals, and at the same time, calculates the sum of the absolute differences of the rear secondary HO2S (bank 1, sensor 2) signals at regular intervals. If the ratio of each absolute difference summation of rear A/F sensor (bank 1, sensor 1) and rear secondary HO2S (bank 1, sensor 2) is a certain value, the PCM detects a malfunction and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type