Check fuel cap light
Can I keep driving? Neither maker tells you to stop the car at once. Mazda says to stop the engine and reinstall the cap (its 2018 Mazda3 manual: park safely off the road first), and warns that driving on with the light lit could turn on the check engine light as well. Ford says you can check the cap yourself, and to visit a dealer if the cap is correctly in place. What each maker's page says
The fuel-filler cap is not sealing the tank: Mazda says it may not be installed properly; Ford lists a cap that is too loose, too tight, missing, dirty or broken.
Yellow / amber
Not defined by regulation: a maker convention
What to do
When it is safe, park and switch the engine off, then take the cap off and refit it until it clicks (Mazda: turn it clockwise until a click is heard). Ford suggests cleaning the cap too. Expect the light to stay on for a while after a correct fit: Mazda says it can take several drive cycles, each one a start after four or more hours with the engine off followed by city and highway driving. If the cap is properly in place and the light still will not go, Ford says to have a dealer diagnose it.
Makes differ: what this light means on your car, the other colours it may use for the symbol and what the car wants you to do are set by the manufacturer, so your car's owner's manual is the authority.
- Symbol
- A fuel pump with a filler cap beside it
- Also called
- Loose gas cap warning (Ford); Check fuel cap warning light (Mazda); Gas cap light
- Colour
- Yellow / amber
- Standard
- None — a maker convention, described here from 2 makers: Ford, Mazda
Where makes differ
Both makers draw the same thing: a fuel pump with a separate filler cap, tilted, beside it. Mazda shows it amber and names it the check fuel cap warning light; its manuals list it for the US and Canada. Ford's support page shows it as a white drawing and calls it the Loose Gas Cap Warning, without naming a colour. If your dashboard has no lamp like this, these two makers' pages cannot tell you how your car reports a loose cap: your own handbook can.
Not defined by regulation: a maker convention
Neither US FMVSS 101 (Tables 1 and 2) nor UN Regulation No. 121 lists this light, so no rule fixes its symbol or its colour. What follows is what the makers cited below say; other makes, and other model years of the same make, may draw it differently.
Neither FMVSS 101 (Tables 1 and 2) nor UN Regulation No. 121 lists a fuel cap tell-tale; both list only the low fuel level warning. Checked 2026-10-16 in the editions cited on /dashboard/more/.
Related lights a regulation does define
Other yellow / amber maker lights
Diesel particulate filter (DPF) lightBox full of dots with a pipe at each end · maker convention
AdBlue (DEF) warning lightLiquid container with a wavy fill line and a drop · also red · maker convention
EPC (electronic power control) lightThe letters EPC · maker convention
Lane assist (lane keeping) lightLane markings running away from you, dashed line in the middle · also green · maker convention
Forward collision warning lightCar seen from behind with radar arcs around it · also red · maker convention
Blind spot monitor lightTwo cars side by side with signal waves between them · maker convention
Adaptive cruise control (ACC) lightSpeedometer dial with a needle · also green · maker convention
Auto Hold lightThe words AUTO HOLD · also green · maker convention
Power steering warning light (EPS)Steering wheel, sometimes with an exclamation mark · also red · maker convention
Water in fuel light (diesel)Fuel pump with water drops beside it · maker convention
Gearbox (transmission) warning lightCog wheel with an exclamation mark · maker convention
Key not detected lightKey with a question mark · maker convention
Bulb failure (exterior light) warningLight bulb with rays and an exclamation mark · maker convention
Hill descent control lightCar pointing down a slope · also green, red · maker convention
Auto stop-start lightLetter A inside a circular arrow · also green · maker convention
Service due (spanner) lightA spanner (wrench) · maker convention
Low engine oil level lightOil can above a wavy level line · maker convention
Frost / icy road warning (snowflake)A snowflake · maker convention
Low washer fluid lightWindscreen with a dashed fountain of spray · maker convention
Key battery low lightKey fob beside a small battery · maker convention
Immobiliser (security) lightCar outline with a key inside it · also red · maker convention
Reduced power (tortoise) lightA tortoise · maker convention
Pedestrian warning sound off or faultyWalking figure with sound waves · maker convention
4WD / AWD warning lightFour wheels joined by axles and a drive shaft · maker convention
Master warning light (triangle with !)An exclamation mark inside a triangle · also red · maker convention
Spanner warning light (a fault, not a service reminder)A spanner (wrench) · maker convention
Foot on brake light (press the brake pedal)A foot pressing a pedal · also green · maker convention
Electric drive system fault light (EV and hybrid)A car outline with an exclamation mark · also red · maker convention
Low drive battery light (electric cars)A battery with plus and minus signs, stacked on more cells · also red · maker convention
Driver attention warning (coffee cup) lightA cup with steam rising from it · also red · maker convention
Speed limiter lightSpeedometer dial with a needle held under a limit mark · also green · maker convention
Adaptive headlight (AFS) lightA headlamp over a two-way curved arrow · maker convention
SOS (eCall) lightThe letters SOS in a frame · also red · maker conventionAll yellow / amber dashboard lights, regulated ones included
What each maker's page says
No regulation defines this light, so it is described from 2 carmakers' own manuals or owner pages: Ford, Mazda. Each was opened with a plain request and is quoted word for word below, with the date it was checked. Everything above the table is our own summary of these quotes; the makers' pages cover their own models only.
| Maker and page | In their words |
|---|---|
| Ford Ford US support — What do the lights on my dashboard mean? (Loose Gas Cap Warning) Checked 2026-10-16 | “It illuminates when there is a problem with the cap, including being too loose, too tight, missing, dirty, or broken. If you see this warning, you can check the cap yourself. The problem might be as simple as tightening it a bit more or cleaning it off. However, if your gas cap is correctly in place, visit your Dealer for a diagnosis.” |
| Mazda Mazda USA owner's manual, 2024 MX-5 — Check Fuel Cap Warning Light (Check Fuel Cap Warning Light) Checked 2026-10-16 | “If the check fuel cap warning light illuminates while driving, the fuel-filler cap may not be installed properly. Stop the engine and reinstall the fuel-filler cap.” |
| Mazda Mazda USA owner's manual, 2018 Mazda3 — Fuel-Filler Cap (Fuel-Filler Cap (U.S.A. and Canada)) Checked 2026-10-16 | “To close the fuel-filler cap, turn it clockwise until a click is heard. […] If the check fuel cap warning light illuminates, the fuel-filler cap may not be properly installed. If the warning light illuminates, park your vehicle safely off the right-of-way, remove the fuel-filler cap and reinstall it correctly. After the cap has been correctly installed, the fuel cap warning light may continue to illuminate until a number of driving cycles have been completed. A drive cycle consists of starting the engine (after four or more hours with the engine off) and driving the vehicle on city and highway roads. Continuing to drive with the check fuel cap warning light illuminated could cause the check engine light to illuminate as well.” |