The check engine light has one job: your car's computer noticed something outside of normal in the engine or emissions system and stored a code about it. The light doesn't tell you what's wrong — that takes diagnosis — but it does tell you your car wants attention.
Steady light vs. flashing light
This is the part worth memorizing: a steady light means "get it checked soon." A flashing light means an active misfire is likely dumping raw fuel into the catalytic converter — pull over when it's safe and don't keep driving on it. That's the difference between a spark plug job and replacing a catalytic converter.
Common causes we see in the shop
- Loose or bad gas cap — yes, really. Cheapest fix on this list.
- Oxygen sensors — they wear out and drag your fuel economy down with them.
- Ignition coils and spark plugs — the usual suspects behind misfires.
- Catalytic converter efficiency codes — often the result of another problem left alone too long.
- Evap system leaks — small vapor leaks that trip emission codes without obvious symptoms.
Why a code reader isn't a diagnosis
A parts-store scan gives you a code like P0420 — but the code points to a system, not a part. Replacing parts off a code alone is how people spend $400 on sensors a $90 diagnosis would have ruled out. We test the circuit and the component before recommending anything.
Quick tip: If the light came on right after a fill-up, tighten the gas cap until it clicks and give it a few days of driving. If the light stays on, come see us.
Our check engine light & diagnostics service uses dealership-level equipment to find the actual cause — and we'll show you what we found before any work begins.
Related service: Check Engine Light & Diagnostics · Questions? (954) 748-4868
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