What’s the result?
It can be a costly mistake. If you fill a diesel car with petrol and start the engine, you will need to have the petrol pumped out of the fuel tank and the engine flushed through at the very least. It’s probably safest to have a new fuel filter put in. But you could be looking at a new fuel pump, injectors, pipework, and fuel tank. If the damage is extensive, it could be cheaper to have a whole new engine.
What to do if you misfuel
First of all don’t even think about starting your car and driving it. In some cars just turning on the ignition primes the fuel pump meaning the damage begins before the engine is running. Go into the service station and ask if someone will help you to push your car to one side so it’s not in the way. Whatever you do, don’t drive your car.
Then call your breakdown company. Any professional misfuelling service should be able to pump the petrol out of your car, flush it through and get you on your way, hopefully with little in the way of lasting damage.
How to prevent it
A simple and cheap way is to get a sticker set from a craft shop and make a ‘diesel’ sticker that you put on your fuel cap and inside the fuel filler flap. Alternatively, there are various devices that are designed to prevent a petrol nozzle going into a diesel tank, while still enabling you to fill up from the black pump. Perhaps the most famous is the Fuel Angel, after its appearance on TV’s Dragon’s Den. The SoloDiesel is also worth looking at.