P0420

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

Exhaust System
- Exhaust manifold front exhaust pipe with Three Way Catalytic Converter (TWC) and attachments. Three Way Catalytic Converter (TWC), Checking
- Exhaust system components removing and installing. Service and Repair
- Mufflers with mounts. Service and Repair
- Three Way Catalytic Converter (TWC), checking. Three Way Catalytic Converter (TWC), Checking

Oxygen Sensors
- Exhaust manifold front exhaust pipe with Three Way Catalytic Converter (TWC) and attachments. Three Way Catalytic Converter (TWC), Checking
- Exhaust system components removing and installing. Service and Repair
- Oxygen Sensor (O2S) and oxygen sensor control before Three Way Catalytic Converter (TWC) checking. Oxygen Sensor and O2S Control Before Catalyst, Checking
- Oxygen Sensor (O2S) heater for oxygen sensors behind Three Way Catalytic (TWC) checking. Oxygen Sensor Heater Behind Catalyst

Note: B1S1 B1S2