A check engine light is annoying, and the instinct is to just make it go away. You can reset it — but before you do, it’s worth understanding what that actually accomplishes (and what it doesn’t). Here’s how to reset, clear, or turn off a check engine light, and when it actually makes sense.
How to reset a check engine light
There are three common ways to clear the light:
- OBD-II scanner (the right way). Plug a code reader into the port under the dashboard and use the “erase” or “clear codes” function. Cheap scanners and many phone apps can do this. This also lets you read the code first — which you should.
- Let it reset itself. If the underlying problem is genuinely fixed, the light will usually turn itself off after several “drive cycles” (a mix of driving conditions over a day or two).
- Disconnecting the battery (not recommended). Yes, it can clear the light, but it also wipes your radio presets, clock, and other learned settings — and it doesn’t fix anything. Skip it.
Will the check engine light come back after you reset it?
Almost certainly — if you didn’t fix the cause. Clearing a code doesn’t repair anything; it just erases the message. The computer keeps monitoring, and the moment it detects the same fault again, the light returns, usually within a few drive cycles. If you reset it and it stays off, that’s actually a good sign the problem was something minor (like a loose gas cap) that’s now resolved.
Light keeps coming back? Call or text Big Tee at (770) 780-0730 — a recurring light means a real fault. We'll find it.
Why you usually shouldn’t just reset it
Here’s the part the “how to turn off your check engine light” videos skip: clearing the code can work against you.
- It erases diagnostic data. When the light triggers, the computer saves a freeze-frame of conditions at that moment. That data helps a mechanic diagnose the problem fast. Clear it, and you throw that away.
- It can hide problems. A recently cleared light can mask issues during an emissions test or a pre-purchase inspection — which is exactly why a smart used-car buyer is suspicious of a car with “no codes” but readiness monitors not set.
- It doesn’t fix the misfire, sensor, or leak that turned it on in the first place.
When it’s OK to clear the light
Clearing the code is reasonable after the actual repair is done — to confirm the fix held and the light stays off. It’s also fine to clear it once after tightening a loose gas cap to see if that was the whole story. The rule of thumb: clear it after you’ve addressed the cause, not instead of addressing it.
The better move: find out why, then turn it off for good
If your check engine light is on, the goal isn’t to silence the messenger — it’s to fix the message. A proper check engine light diagnostic reads the codes, tests to confirm the real cause, and fixes it so the light stays off on its own. No resets, no guessing, no coming back next week.
New to the whole thing? Start with our overview of what the check engine light means and what to do — and if it’s flashing, read this first, because that one’s urgent.
Written by the Big Tee Auto Repair team — 29 years of mobile and shop mechanic experience in Decatur, GA and Metro Atlanta.