Misfuelling is a common mistake that can cause serious damage to your vehicle if not handled correctly. Whether you've put petrol in a diesel car or vice versa, acting quickly can save you from costly repairs. Every year, thousands of UK drivers make this mistake, so you are not alone. Here’s what you need to do if you’ve accidentally filled up with the wrong fuel.
1. Don’t Start the Engine
The most important step is to avoid starting your car. Turning on the ignition can circulate the incorrect fuel through your engine, increasing the risk of damage. If you realise your mistake while still at the pump, leave the car switched off. If you’ve already inserted the key and switched on the ignition, stop immediately.
2. Push the Car to a Safe Location
If your car is blocking a fuel pump or a busy area, ask for assistance to move it to a safe place. Most petrol stations will have staff who can help. It’s best to inform the station attendants, as they may be able to provide guidance or direct you to a misfuelling specialist.
3. Call for Professional Assistance
Misfuelling specialists can drain and flush your fuel system, preventing any long-term damage. Many breakdown providers offer this service, so contact your roadside assistance provider or a dedicated misfuelling service. Some companies operate mobile units that can come to your location, minimising disruption to your day.
4. Know the Risks of Misfuelling
Understanding the potential damage misfuelling can cause is crucial. The severity depends on the type of mistake and how long the incorrect fuel has been in your vehicle.
- Petrol in a Diesel Car: Petrol acts as a solvent in a diesel engine, reducing lubrication and potentially causing severe damage to the fuel pump and injectors. Diesel engines rely on the fuel for lubrication, so petrol can cause increased friction and wear.
- Diesel in a Petrol Car: Diesel is thicker and doesn’t ignite properly in a petrol engine, leading to misfiring, excessive smoke, and possible engine failure. Even a small amount can clog the fuel injectors and damage components.
5. Drain and Refill the Tank
If a professional drains the incorrect fuel, they will usually flush the system before refilling it with the correct type. Never attempt to siphon fuel yourself, as modern cars have anti-siphon devices and fuel vapours can be hazardous. Once the system is cleaned and refilled, a mechanic may check for any residual damage before allowing you to drive away.
6. Check for Warning Signs if You’ve Driven the Car
If you only realised your mistake after driving, look out for symptoms such as:
- Loss of power
- Engine knocking or misfiring
- Excessive smoke from the exhaust
- Difficulty starting the car
- Unusual smells from the engine bay
If you experience any of these, stop the vehicle immediately and call for assistance. The quicker you act, the lower the risk of serious engine damage.
7. Prevent Misfuelling in the Future
Avoiding misfuelling can save you time, money, and stress. Here are some practical ways to prevent making the same mistake again:
- Double-check the fuel label on the pump before refuelling.
- Keep a reminder sticker near your fuel cap or on the dashboard.
- If you drive multiple cars, be extra cautious when switching between petrol and diesel vehicles.
- Use a fuel cap misfuelling prevention device if available.
- Always refuel when alert, avoiding distractions at the pump.
8. What If You Don’t Notice Immediately?
If you only realise the mistake hours or days later, but have not driven the car, do not attempt to start it. Contact a professional who can assess whether draining the tank is necessary. In some cases, small amounts of incorrect fuel may not cause significant damage, but it’s always best to seek expert advice.
Putting the wrong fuel in your car is an easy mistake, but with the right response, you can minimise the damage and costs. The key is to act quickly, avoid starting the engine, and call for professional help. If you’ve already driven, stop as soon as possible to prevent further complications. Taking preventive measures, such as checking fuel labels and using reminders, can save you from the hassle in the future. If in doubt, always seek professional assistance rather than attempting to resolve the issue yourself.
