Symptom
Visible fuel leak
Fuel visible on the engine, lines or ground. Stop using the vehicle and keep people away from it until it has been inspected — high-pressure fuel leaks are a fire hazard.
Also described as: fuel leaking, leaking fuel, petrol leak, diesel leak, fuel on the ground, wet with fuel, gas leak, نشت بنزین, چکه کردن سوخت, fuga gasolina, pierde combustible, gotea gasolina, fuga gasoil, تسريب بنزين, تنقيط وقود, تسرب سولار
Some causes mean you should stop driving
1 of the 2 codes that produce this symptom indicate a fault where continuing to drive risks damage or is unsafe. If the symptom is sudden or severe, treat it as one of those until a scan says otherwise.
What this usually means
Stop using the vehicle and keep people away from it until it has been inspected. High-pressure fuel leaks are a fire hazard. This is one of the few entries in this corpus where the correct first action is to stop rather than to diagnose.
The quantity is not the measure of the danger. A high-pressure line can leak a spray fine enough to ignite on a hot surface while leaving very little on the ground, and a small drip onto a hot exhaust or turbocharger is more dangerous than a larger one onto cold tarmac. Destination and pressure decide urgency, not volume.
Recover rather than drive, including to a nearby garage. The heat of the engine bay is highest immediately after running, and moving the vehicle is exactly when the leak is pressurised and the surfaces are hot.
Do not attempt to work on a pressurised system. Modern high-pressure diesel and direct-injection petrol rails hold pressure after the engine stops, and releasing a fitting without depressurising properly is dangerous — injection-pressure fuel can penetrate skin.
Where the leak is tells you what it is. Around the injectors or rail, the high-pressure side. At the filter or its unions, the supply. Under the rear, the tank, its sender flange or the vent lines. A leak that only appears with the engine running is on the pressurised side; one that leaks while parked is on the tank or supply side.
Note anything that was recently worked on. A union not torqued, a seal reused, or a line routed against something it now rubs on are common and preventable causes.
Working through it
| What you find | Likely cause | How to confirm it | What fixes it |
|---|---|---|---|
| Any visible liquid fuel, any quantity | A leak — quantity does not determine danger | Nothing to confirm at the roadside. Stop, keep ignition sources away, and do not restart to reposition the vehicle. | Recover on a flatbed. Repair before use, whatever the apparent size. |
| Leak only with the engine running | The pressurised side — supply or high-pressure rail | Inspect with the system depressurised by the manufacturer's procedure. Never crack a fitting on a live rail. | Renew the line, union or seal. Torque to specification; these are not fittings to judge by feel. |
| Leak while parked, strongest at the rear | The tank, its sender flange seal, or the vent and filler lines | Inspect above the tank with it lowered or through the access panel. Look for staining as well as wet fuel. | Renew the seal or hose. Reused sender seals are a common cause of a leak that returns. |
| Fuel dripping onto the exhaust or turbocharger | The most dangerous configuration regardless of how slow the leak is | Do not run the engine to look. Assess cold and treat as immediate. | Repair and clean the hot components thoroughly. Residual fuel on a manifold ignites on the next run. |
| Appeared immediately after fuel system work | A union not torqued, a seal reused, or a line rubbing where it was rerouted | Retrace the work. This is preventable and dates itself precisely. | Reseal and re-torque with new seals, and secure the line clear of what it touches. |
| Strong smell but nothing visible | Possibly a vapour leak rather than liquid — a different urgency but still a fault | Smoke-test the evaporative system. See the fuel-smell entry, which covers the vapour side. | Repair the vapour leak. Do not assume the absence of liquid means the absence of a leak. |
-
Any visible liquid fuel, any quantity
- Likely cause
- A leak — quantity does not determine danger
- How to confirm it
- Nothing to confirm at the roadside. Stop, keep ignition sources away, and do not restart to reposition the vehicle.
- What fixes it
- Recover on a flatbed. Repair before use, whatever the apparent size.
-
Leak only with the engine running
- Likely cause
- The pressurised side — supply or high-pressure rail
- How to confirm it
- Inspect with the system depressurised by the manufacturer's procedure. Never crack a fitting on a live rail.
- What fixes it
- Renew the line, union or seal. Torque to specification; these are not fittings to judge by feel.
-
Leak while parked, strongest at the rear
- Likely cause
- The tank, its sender flange seal, or the vent and filler lines
- How to confirm it
- Inspect above the tank with it lowered or through the access panel. Look for staining as well as wet fuel.
- What fixes it
- Renew the seal or hose. Reused sender seals are a common cause of a leak that returns.
-
Fuel dripping onto the exhaust or turbocharger
- Likely cause
- The most dangerous configuration regardless of how slow the leak is
- How to confirm it
- Do not run the engine to look. Assess cold and treat as immediate.
- What fixes it
- Repair and clean the hot components thoroughly. Residual fuel on a manifold ignites on the next run.
-
Appeared immediately after fuel system work
- Likely cause
- A union not torqued, a seal reused, or a line rubbing where it was rerouted
- How to confirm it
- Retrace the work. This is preventable and dates itself precisely.
- What fixes it
- Reseal and re-torque with new seals, and secure the line clear of what it touches.
-
Strong smell but nothing visible
- Likely cause
- Possibly a vapour leak rather than liquid — a different urgency but still a fault
- How to confirm it
- Smoke-test the evaporative system. See the fuel-smell entry, which covers the vapour side.
- What fixes it
- Repair the vapour leak. Do not assume the absence of liquid means the absence of a leak.
Codes that produce this symptom (2)
Listed with the codes that most typically present this way first — the likeliest place to start.
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Others with this symptom
Be the first to write this up
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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