A car that smells like gas usually has a fuel leak or a vapor leak. The common sources are a loose or damaged gas cap, a leaking fuel injector seal or fuel line under the hood, a failed evaporative emissions part such as the charcoal canister or purge valve, or an engine running rich so unburned fuel comes out of the exhaust. A strong smell of raw fuel is a fire risk: park outside, away from ignition sources, and have it checked before driving.
Where the smell comes from
| When you smell it | Likely source |
|---|---|
| Right after starting, under the hood | Injector O-rings, fuel rail or lines leaking under pressure |
| After filling up | Gas cap, filler neck, or an evaporative canister flooded by topping off |
| Inside the cabin | Fuel pump access seal under the rear seat on some cars, or exhaust entering the cabin |
| While driving, from the exhaust | Rich running: injectors, fuel pressure, O2 sensors; see exhaust smoke colors |
| When parked, near the tank | Tank, sending unit seal, or lines along the frame |
Smells like gas but no leak
With no drips, check the gas cap seal first, then the evaporative system. Rich running is the other common cause: a leaking injector, a failed fuel pressure regulator or a faulty O2 sensor can dump extra fuel, often with rich codes such as P0172 or P0175 and black smoke.
Smells like gas when starting
Fuel systems hold high pressure, and a weeping injector O-ring or rail fitting shows up most when cold seals contract. A brief whiff from the exhaust on a cold start can be normal, because engines run rich when cold, but a lasting smell under the hood is not; see fuel injector symptoms.
Smells like gas after filling up
Stop filling at the first click of the pump. Topping off can push liquid fuel into the evaporative canister, which is designed for vapor only, and cause a lasting smell and check engine light. Make sure the cap clicks shut.
What to do
- Look under the car and under the hood for wet spots or drips; do not smoke or create sparks.
- Check that the gas cap seals and is not cracked.
- Scan for evaporative and fuel trim codes; see check engine light.
- Have any leak under pressure repaired before driving.
Other fuel smells
A smell like burning oil or coolant is a different problem; see burning smell from car. A fuel filter or line replaced recently should be checked for a loose fitting; see fuel filter.
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