Symptoms
- Light came on shortly after or during a fill-up
- Car drives completely normally
- May hear a faint hissing near the fuel door when opening the cap
Likely causes
- CommonGas cap not tightened fullyMost caps need several audible clicks to seal.
- CommonCracked or worn gas cap sealRubber gaskets dry out and stop sealing over time.
- PossibleGas cap left off or lost after fill-upEasy to forget to replace after paying at the pump.
- Less commonEvaporative system hose or valve leakIf tightening the cap doesn't fix it after a few drives, look elsewhere in the system.
What to do
- Pull over safely and check that the gas cap is present and undamaged.
- Tighten the cap until it clicks 2–3 times or stops turning.
- Inspect the rubber seal on the cap for cracks or a stiff, brittle feel.
- If the seal looks worn, replace the cap with a new one that fits your car.
- Drive normally for several trips; it can take multiple engine cycles for the light to turn off on its own.
- If the light hasn't cleared after about a week of driving, have the code read to confirm it's the evap system.
- Ask a parts store to scan it for free if you want to double check before waiting it out.
Tools and parts
Replacement gas capSearch: “OEM-fit locking or non-locking gas cap for your car”
When to call a pro
See a mechanic only if the light doesn't clear after a week of normal driving with a tight, undamaged cap.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.