P0420

SAE VAG Description
P0420 16804 Catalyst System Efficiency Below Threshold Bank 1

Catalytic converter
- Three Way Catalytic Converter (TWC), checking. Catalytic Converter, Checking

Oxygen sensor and oxygen sensor control before catalytic converter
- Oxygen sensor and oxygen sensor control before catalytic converter, checking. Oxygen Sensor and Oxygen Sensor Control Before Catalytic Converter, Checking
- Check wiring diagram.

Oxygen sensor and oxygen sensor control behind catalytic converter
- Oxygen sensor and oxygen sensor control behind catalytic converter, checking. Oxygen Sensor and Oxygen Sensor Control Behind Catalytic Converter, Checking
- Check wiring diagram.

Oxygen sensor and oxygen sensor control in center catalytic converter
- Oxygen sensor and oxygen sensor control in center catalytic converter, checking (engine code BBW).
- Check wiring diagram.