What to Do If You Put the Wrong Fuel in Your Car

By Mr. GillOctober 1, 2026

Put petrol in a diesel or diesel in a petrol car? These are the immediate steps to take before the wrong fuel circulates.

Do not start the engine

If you notice the mistake while still at the pump, do not start the engine or turn the ignition on. Starting can circulate contaminated fuel through the fuel system and increase the risk of damage. Tell service-station staff and ask for help moving the car only if it can be done safely without starting it.

If you have already started or driven it

Stop as soon as it is safe, switch off the engine and do not restart it. Tell the mechanic exactly what happened, including the fuel type, approximate amount, vehicle and whether the engine was started or driven. Those details help determine the next step.

Avoid trying a DIY fix

Do not add more fuel to dilute the mixture or attempt to drain the tank yourself. Fuel is hazardous and the correct procedure depends on the vehicle and what happened. Arrange suitable professional assistance and follow the vehicle manufacturer’s advice.

Keep yourself safe

If the vehicle is in a dangerous position, move away from traffic and follow local road-safety advice. Do not push it if doing so puts you or others at risk. Use roadside assistance if the vehicle needs to be moved.

Get help in Cairns

Gill Auto Care provides wrong-fuel assistance subject to location and availability. Call or text with your vehicle, location, mistaken fuel and whether the engine has been started so the next steps can be discussed.

Need help with your vehicle?

Contact Gill Auto Care about wrong fuel or contact Gill Auto Care to discuss your vehicle, location and the work required. Mobile appointments are available across Cairns and surrounding suburbs, subject to service and availability.

This guide is general information. Always follow the owner’s manual for your vehicle and seek professional advice for warning lights, safety concerns or repairs.