What To Do if you Put the Wrong Fuel in Your Car

Every 3.5 minutes someone puts the wrong fuel in their car. So what should you do if it happens to you? Read on to find out...

• Do not start the engine
  
• Do not operate your electrical unlocking because unlocking can cause automatic priming of the fuel system in some cars.
  
• Get the car pushed to a safe place on the forecourt
  
• Call your breakdown service, or a local garage if you don't belong to one
  
• If you have already started the engine and driven off, then stop as soon as you realise your mistake or you may get half a mile or so down the road before your car gives up on you.
  
• Even a small amount of the wrong fuel can seriously damage the car’s fuel system or reduce the efficiency of the catalyst.

How to make sure it doesn't happen to you...

Think about what car you are driving and what fuel it takes.

If you’re not sure check the marking around the filler cap. Never assume.

Always double check that you pick up the correct pump nozzle. Read the label on the pump.

Most pumps use a colour coding:
Green smaller nozzle for unleaded petrol
Black large nozzle for Diesel

Due to the larger nozzle, it is more difficult to fill a petrol car with diesel. However, it is all too easy to fill a diesel car with petrol so always take extra care if you have a diesel car.

Never force a larger nozzle into a smaller filler neck. It will be the wrong fuel.

THINK BEFORE YOU FILL
 

What happens if you do fill your car with the wrong fuel?

Don't start the engine and call your breakdown service or a local garage

The breakdown services will not drain the fuel on the spot but can arrange to take the car to your dealer or a local garage

If you are especially lucky, they will be able to drain the tank and clean the hoses, purge the fuel from pumps and replace the filter.

If you are not so lucky, the job will be considerably bigger (in the case of executive cars it can mean a replacement engine at a cost of up to £12,000)

Then it's a case of contacting your insurance company, fingers crossed, to see if you are covered.  In principle that kind of accidental damage can be covered by comprehensive insurance, says the Association of British Insurance, but it is well worth checking your own policy as very often they are specifically excluded from motor policies, especially third party-only.

What damage is caused to the car?

For modern diesel engines because they use extremely high injection pressures the composition of the fuel is critical. Any petrol present can cause damage to the pump elements, and the seals can be damaged by compounds found in petrol. Petrol wrecks a diesel engine lubrication process, and is particularly damaging to its costly, high-pressure pump, fuel injection system and filters.

For a petrol engine the combustion efficiency of an engine designed for petrol will be very poor if it’s fed diesel fuel, and the resulting unburned fuel passing through to the exhaust can cause the catalyst to overheat.

Why is it happening more often now?

The possibility of getting the wrong fuel has risen pretty much in line with the increase in the number of diesel cars – which now account for one in four new cars in the UK.

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