Vehicle system
Emissions Control Codes: Catalyst, EVAP and EGR
Codes for the catalytic converter, the EVAP system that captures fuel tank vapors, the EGR valve and secondary air injection. These are the codes that most often cause a failed emissions inspection.
Most of them do not change how the vehicle drives, but they do affect what it emits and the result of the inspection. A catalyst code is usually the consequence of another fault, such as misfires or oil consumption, which must be fixed before replacing the converter.
Most searched codes in this system
- P0420 and P0430: catalyst efficiency below threshold.
- P0440 to P0457: EVAP system leaks and circuits.
- P0401 and P0402: EGR flow insufficient or excessive.
- P0411: secondary air injection flow.
- P0496: EVAP purge flow with the valve commanded closed.
What to check first
- For EVAP codes, start with the gas cap and its seal.
- Before replacing a catalytic converter, rule out misfires, a rich mixture and exhaust leaks.
- Clean the EGR valve and its passages if they are clogged with carbon.
- Complete the readiness monitors with a drive cycle before the inspection.
All codes in this system
174 codes, page 1 of 2