Emission control codes
Quick answer
Catalyst efficiency, evaporative emission leaks, exhaust gas recirculation and secondary air injection. There are 31 codes in this group on the site, plus 27 pages covering specific makes.
- P0400EGR Flow Malfunction
- P0401EGR Flow Insufficient Detected
- P0402EGR Flow Excessive Detected
- P0403EGR Circuit Malfunction
- P0404EGR Circuit Range/Performance
- P0405EGR Sensor A Circuit Low
- P0406EGR Sensor A Circuit High
- P0411Secondary Air Injection System Incorrect Flow Detected
- P0412Secondary Air Injection System Switching Valve A Circuit Malfunction
- P0418Secondary Air Injection System Relay A Circuit Malfunction
- P0420Catalyst System Efficiency Below Threshold (Bank 1)
- P0421Warm Up Catalyst Efficiency Below Threshold (Bank 1)
- P0422Main Catalyst Efficiency Below Threshold (Bank 1)
- P0430Catalyst System Efficiency Below Threshold (Bank 2)
- P0431Warm Up Catalyst Efficiency Below Threshold (Bank 2)
- P0432Main Catalyst Efficiency Below Threshold (Bank 2)
- P0440Evaporative Emission System Malfunction
- P0441Evaporative Emission System Incorrect Purge Flow
- P0442Evaporative Emission System Leak Detected (Small Leak)
- P0443Evaporative Emission System Purge Control Valve Circuit Malfunction
- P0446Evaporative Emission System Vent Control Circuit Malfunction
- P0449Evaporative Emission System Vent Valve/Solenoid Circuit Malfunction
- P0451Evaporative Emission System Pressure Sensor Range/Performance
- P0452Evaporative Emission System Pressure Sensor Low Input
- P0455Evaporative Emission System Leak Detected (Large Leak)
- P0456Evaporative Emission System Leak Detected (Very Small Leak)
- P0457Evaporative Emission System Leak Detected (Fuel Cap Loose/Off)
- P0491Secondary Air Injection System Insufficient Flow (Bank 1)
- P0492Secondary Air Injection System Insufficient Flow (Bank 2)
- P0496Evaporative Emission System High Purge Flow
- P0497Evaporative Emission System Low Purge Flow