P0423 AUDI – Heated Catalyst Efficiency Below Threshold Bank 1

P0423 AUDI Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P0423 AUDI Possible Causes

Air leak before catalytic converter,Faulty oxygen sensor,Faulty Catalytic Converter

P0423 AUDI Description

The Engine Control Module (ECM) monitors the switching frequency ratio of heated oxygen sensors 1 (front O2 sensor) and heated oxygen sensors 2 (rear O2 sensor). A three way catalyst converter (Manifold) with high oxygen storage capacity will indicate a low switching frequency of heated oxygen sensor 2. As oxygen storage capacity decreases, the heated oxygen sensor 2 switching frequency will increase. When the frequency ratio of heated oxygen sensors 1 and 2 approaches a specified limit value, the three way catalyst malfunction is diagnosed.