Check Engine Light: Solid vs. Flashing, and What to Do

Solid light: get it checked soon

A steady check engine light means the engine computer found a fault and stored a code. It usually isn't an emergency, but don't ignore it for months — small problems can turn into expensive ones. If the car also runs rough, loses power, overheats or makes new noises, get it looked at right away.

Flashing light: ease off now

A flashing check engine light usually means the engine is actively misfiring. Unburned fuel can overheat and ruin the catalytic converter quickly. Slow down, avoid hard acceleration and highway speeds, and get it checked as soon as possible — or have it looked at where it sits.

Common causes

• Loose or bad gas cap — the simplest one. Tighten it until it clicks; the light may go off after a few drives.
• Oxygen sensor — hurts fuel economy and can eventually damage the catalytic converter.
• Misfires — often worn spark plugs or a failing ignition coil.
• Mass airflow sensor — can cause rough idle or hesitation.
• EVAP system leaks or valves
• Catalytic converter efficiency codes — often misdiagnosed; sensors and exhaust leaks should be checked before replacing a converter.

A code is a clue, not a diagnosis

A basic code reader tells you where to look, not always what's broken. We use a professional full-system scan tool with live data and component tests, so you fix the cause instead of guessing with parts.