Check Engine Light Causes: From Gas Cap to Catalytic Converter
The check engine light can mean a $0 fix or a $2,000 repair. Here's how to triage it before you panic.
Solid vs flashing — it matters
A solid check engine light means the computer logged a fault that needs attention — soon, not immediately. A flashing light means a misfire is happening right now and you risk damaging the catalytic converter if you keep driving. Pull over, call for a tow or mobile diagnosis.
Most common codes we see
Loose or failing gas cap (P0457). Oxygen sensor failure (P0131-P0161 family). Catalytic converter efficiency (P0420, P0430). Misfire detected (P0300-P0306). Mass airflow sensor (P0101). Most can be confirmed in a 30-minute mobile diagnostic visit.
FAQ
Can I keep driving with the check engine light on?
If it's solid and the car runs normally, yes — but get it diagnosed within a week. If it's flashing, stop driving and call.
Will reading the code fix the problem?
No. A code is a starting point. A real diagnosis uses live data and proper testing to identify the root cause.