Check Engine Light: Steady vs Blinking (EPA Guide)
What the light is telling you, based on EPA fact sheets.
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Since 1996, cars and light trucks have OBD-II, which watches the engine, transmission and emissions parts. The check engine light is how it talks to you.
At start-up
EPA says the light should flash briefly when you turn on the ignition and then stay off.
Steady light
The system found a problem that may waste fuel, shorten engine life or raise pollution. EPA’s steps:
- Do not panic. Seek attention soon.
- At your stop, check that the gas cap is not loose or missing.
- If the light stays on after a few short trips, get the car serviced.
Blinking light
EPA says this means a severe problem such as a catalyst-damaging misfire. Get it fixed as soon as possible, keep time on the road short, and avoid high speed and heavy loads such as towing.
Read the code yourself
A shop uses a scan tool on the port under the dash. A home OBD2 scanner reads the same codes.
Steady vs blinking at a glance
| Light | What EPA says it means | What to do |
|---|---|---|
| Brief flash at start-up | Bulb and system check | Nothing, if it goes off |
| Steady | A problem that may waste fuel, shorten engine life or raise pollution | Check the gas cap, then get service if it stays on after a few short trips |
| Blinking | A severe problem such as a catalyst-damaging misfire | Get it fixed as soon as possible; avoid high speed and heavy loads |
Related
Frequently asked questions
Is it safe to drive with the check engine light on?
EPA says a steady light means seek attention soon. A blinking light means a severe problem such as a catalyst-damaging misfire. Minimize driving and avoid high speed and heavy loads.
Can a loose gas cap turn on the light?
Yes. EPA names a loose or missing gas cap as one cause and says to check it first.
