P0434 MERCEDES-BENZ – Heated Catalyst Temperature Below Threshold Bank 2

P0434 MERCEDES-BENZ Possible Symptoms

Engine Light ON (or Service Engine Soon Warning Light)

P0434 MERCEDES-BENZ Possible Causes

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

P0434 MERCEDES-BENZ 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.