Check Engine Light
A steady (not flashing) check engine light means the computer logged a problem. It is worth reading the code, but it is not usually an emergency.
Should you keep driving?
A steady light is usually safe to drive on short-term, but ignoring it can turn a small fix into a big one.
Common causes
Loose or bad gas capA surprisingly common trigger — a poor seal sets an evaporative-system code.
Oxygen or MAF sensorAging sensors are a frequent cause and hurt fuel economy.
Catalytic converterA "cat efficiency" code can be pricey and is worth diagnosing early.
Misfire or vacuum leakOften paired with rough running — see the codes to know for sure.
Rather have a pro handle it? Find a vetted local mechanic.