What Happens When You Put Petrol in a Diesel Car & How to Fix It

Accidentally filling a diesel car with petrol is a common mistake that can lead to engine damage if not addressed promptly. Understanding what happens chemically, the damage timeline, and the proper repair process can help you act quickly and minimise costs.

When petrol is introduced into a diesel engine, it disrupts the fuel system’s chemistry. Diesel engines rely on the lubricating properties of diesel fuel to keep components like the fuel pump and injectors functioning smoothly. Petrol, however, is less viscous and lacks the lubricating qualities of diesel. This can cause increased wear and potential damage to critical parts. Additionally, petrol’s lower flash point means it ignites more easily, which can lead to misfiring or knocking if the engine is started.

The damage timeline depends on how much petrol is in the tank and whether the engine is started. If the engine is turned on, petrol circulates through the fuel system, diluting the diesel and causing immediate lubrication issues. This can lead to rapid wear of the fuel pump, injectors, and other components. The longer the engine runs on petrol, the greater the risk of severe damage, including potential engine failure. If the vehicle remains off and the petrol is removed quickly, the risk of damage is significantly reduced.

The recommended course of action is to avoid starting the engine altogether. Turning on the ignition can circulate petrol through the system, increasing damage risk. Instead, contact a professional misfuel recovery service like EEK Mechanical. We dispatch a NZIFDA-certified tow truck to collect your vehicle and transport it to a certified workshop for manufacturer-spec fuel system recovery. Our process involves carefully removing the contaminated fuel and thoroughly cleaning the fuel system to prevent residual petrol from causing future issues.

What to do right now: If you realise you’ve put petrol in your diesel car, do not start the engine. Contact us immediately at 0800 769 000. We operate 24/7 and will dispatch a tow truck to collect your vehicle promptly. Do not attempt to drive or start the engine, as this can lead to costly repairs and extensive damage.

Remember, timely action is key to minimising damage and ensuring your vehicle is properly repaired. Our certified workshops specialise in manufacturer-spec fuel system recovery, ensuring your car is returned to optimal condition. For peace of mind and expert assistance, call EEK Mechanical now at 0800 769 000. We’re here to help, anytime, day or night.