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Warning lightsUpdated 2026-10-24

Check engine light comes on and goes off

What it means

A check engine light that comes and goes can mean the engine computer found an intermittent fault, saved a pending or history code, and may turn the lamp back on after a few drive cycles if the problem is still there. Ignoring it can hide a misfire, increase fuel use, or let a repair get costlier later.

Safety first

  • If the check engine light flashes, the engine misfires badly, or the vehicle loses power, stop driving as soon as it is safe. From the article: Is it safe to ignore a check engine light that went back off? > When to stop driving and get help now

Fix it step by step

Try the steps in order, easiest and safest first. After each one, tell us if the problem is gone.

Step 1 of 2

  1. Step 1: Use a scan tool to check current and history dataLow risk
    1. A scan tool should be used even if the dash light is off.
    2. Check current codes, pending codes, stored history, and permanent codes.
    3. Review freeze-frame data, then compare it with the worksheet notes so you can match the trip conditions that caused the fault.

    Then check whether the problem is still there.

    From the guide section: Can a check engine light go off but still have a code? > How to use a scan tool to check current and history data

  2. Step 2: When to schedule service soonLow riskIf nothing else worked
    1. If the light has come and gone more than once, schedule service and bring the worksheet.
    2. The repeated pattern helps separate a passing monitor from a fault that is still active.
    3. Multiple test drives may be needed to confirm it.

    Then check whether the problem is still there.

    From the guide section: Is it safe to ignore a check engine light that went back off? > When to schedule service soon

Still broken after every step?

That is every step we have for this problem. Write down what you saw and which step you reached, then ask a qualified mechanic to look at the car. If it feels unsafe to drive, stop and call roadside help.

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✅ Glad it is fixed.

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Frequently asked questions

Why does my check engine light come on and go off?

It usually means the engine computer detected an intermittent fault, stored code data, and then passed the system on a later drive cycle. The light may go off before the problem is fully gone, so scan for pending, stored, and permanent codes before assuming it fixed itself.

Which step should I try first?

Start with "Use a scan tool to check current and history data". The steps run from the easiest and safest to the hardest, so you can stop as soon as the problem is gone.

Sources

The steps above come from VFixCars articles.