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
On the your car, this warning indicates reduced catalytic converter efficiency. Sometimes the converter is genuinely failing; often it is an upstream problem (misfire, O2 sensor) that damaged it.
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. |