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Petrol in a diesel car
Petrol in a diesel is the misfuel we see most. The green nozzle fits a diesel filler neck easily, so it happens to careful drivers every day — especially in a new, hire or company car.
Do this now
- 1Don't start the engineDon't turn the ignition on either. Keyless? Keep the fob away from the car.
- 2Neutral and push clearAsk staff to help push the car away from the pump.
- 3Tell the cashierThey deal with misfuels every week.
- 4Call Mr FuelFixed price and arrival time on the phone.
On a motorway? Get behind the barrier first. In danger, call 999.
Diesel lubricates its own high-pressure fuel pump. Petrol is a solvent: it strips that lubrication away, and if the engine runs, the pump and injectors can start to wear metal on metal. That is where four-figure repair bills come from. Caught early, it is a straightforward drain and flush.
Signs you need us
- You've just realised at the pump or the till
- The car is knocking, juddering or smoking after filling up
- The engine cut out within a few miles of the forecourt
- Warning lights came on and power dropped away
- The car will not restart after filling up
How we fix it
- 1Make safeWe confirm where you are, check you're somewhere safe and tell you what not to touch. On a forecourt or car park, the car stays put.
- 2DrainOur technician connects a sealed, ADR-compliant pump to the fuel system and removes every drop of contaminated fuel from the tank.
- 3FlushWe flush the tank and lines with clean diesel. If the engine was started we also purge the filter and fuel rail, and change the filter if needed.
- 4Refuel and testFresh diesel goes in, we prime the system, start the engine and check it runs clean before we leave.
- 5Dispose legallyThe contaminated fuel is taken away and disposed of by a licensed carrier. You get a receipt and job report for your insurer.
Good to know
- Running the engine circulates petrol through the high-pressure pump and injectors.
- Driving on until it cuts out can mean pump, injector, filter and line replacement.
- Many manufacturer warranties and some insurance policies exclude misfuel damage caused by driving on.
FAQs
Petrol in a diesel car: questions
Can I drive with a small amount of petrol in my diesel?+
We don't recommend it. Older diesels could tolerate a splash, but modern common-rail engines run at very high pressure and depend on diesel's lubricity. Even a few litres of petrol can damage the pump. The cost of a drain is small next to the cost of a fuel pump.
I turned the key but didn't start the engine. Is that a problem?+
Possibly. On many cars, turning the ignition on primes the fuel pump and pulls fuel into the lines. Tell us when you call and we'll drain the lines as well as the tank.
How long does it take?+
Most drains take 30 to 45 minutes from when the technician arrives. If the engine has been run, allow an hour or so for the extra flushing.
Will this affect my warranty?+
A professional drain with a written job report is what most manufacturers and insurers want to see. The damage that voids warranties usually comes from driving on, not from the drain.
Do I need to tell my insurer?+
Check your policy. Some include misfuel cover, some exclude it. We give you an itemised receipt and report either way, so you can claim if you're covered.
Related
Other problems we fix
Petrol in diesel help near you
Wrong fuel? Don't start the engine.
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