Urgency: High
Catalytic Converter Warning Light
Have this checked promptly. It is not an immediate stop, but do not ignore it for long.
What the Catalytic Converter Warning Light Means
A catalytic converter warning on a your car (usually shown via the check engine light with a P0420-type code) means the cat is no longer cleaning exhaust efficiently, or a downstream oxygen sensor is misreading. It affects emissions and can fail an inspection.
Common Causes
- Aging or failing catalytic converter
- Faulty downstream oxygen sensor
- Engine misfire damaging the cat
- Rich fuel mixture
- Exhaust leak near the sensors
How to Fix It
- Scan for the specific catalyst code (e.g. P0420/P0430)
- Fix any misfire or fuelling issue first
- Test the downstream oxygen sensor
- Check for exhaust leaks around the sensors
- Replace the converter only once upstream causes are ruled out
Related DTC Codes
| Code | Meaning |
|---|---|
P0420 | Catalyst System Efficiency Below Threshold (Bank 1) The catalytic converter on bank 1 is no longer cleaning exhaust efficiently, or the downstream O2 sensor is faulty. |
P0430 | Catalyst System Efficiency Below Threshold (Bank 2) The bank 2 catalytic converter efficiency has dropped below the threshold monitored by the ECU. |