Check Engine Light

A check engine light can be triggered by emissions faults, ignition problems, fuel system issues, sensor failures, or engine performance problems. A scan tool is the first step.

Common Causes

• Loose or faulty gas cap
• Oxygen sensor failure
• Catalytic converter efficiency issues
• Ignition misfires
• EVAP system leaks
• Mass airflow sensor problems

Related OBD Codes

• P0420 — Catalyst System Efficiency Below Threshold
• P0171 — System Too Lean
• P0300 — Random/Multiple Cylinder Misfire
• P0442 — EVAP System Small Leak Detected
• P0101 — Mass Air Flow Sensor Range/Performance

Common Repairs

• Scan and diagnose stored trouble codes
• Replace faulty oxygen sensor
• Repair EVAP leak
• Replace spark plugs or ignition components
• Clean or replace mass airflow sensor

What Should You Do Next?

Not sure where to go next? Use these tools to continue diagnosing or estimate your repair.

Estimate This Repair

Use the TorqueMech estimator to calculate a repair estimate based on your vehicle and service.

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