DTC 4-4-3 Three Way Catalytic Converter Efficiency

4-4-3 THREE-WAY CONVERTER EFFICIENCY

Preconditions for DTC
^ The ECM continuously monitors the Three-Way Converter's (TWC) efficiency by comparing the signal from the rear Heated Oxygen Sensor (HO2S) with the signal from the front Heated Oxygen Sensor (HO2S). When the TWC's efficiency deviates too much, the ECM sets DTC 4-4-3.

Substitute value
^ None.

Fault sources
^ Uneven compression.
^ Air leakage in the intake system.
^ Air leakage in the exhaust system.
^ Incorrect fuel pressure.
^ Defective TWC.

Fault symptoms
^ May result in poorer performance.