Check engine light (steady): what it means and what to do

What it means

• Mazda lists engine control, emission control and transmission control problems as triggers, and also a missing or loose fuel cap, or a very low fuel level.
• OBD can spot emissions-related failures before you notice any drivability problem.
• The light can go off by itself: if the OBD system checks the problem three consecutive times and doesn't see it, it turns the light off. A loose gas cap that you tighten is a common example.

What to do

1. Check that the gas cap is tight.
2. Read the stored codes with an OBD2 scanner and look them up in our directory.
3. If the car drives normally, book a diagnosis soon. If it runs badly, drive gently and get it checked as soon as possible.
4. Mazda warns: don't disconnect the battery while the light is on or flashing.

Sources

1. Mazda USA owner's manual (2024 CX-30): Check engine warning light
2. Wisconsin Vehicle Inspection Program: OBD FAQ