| Car Breakdowns | << Back to Education |
Filled with the wrong fuel?
If you have just accidentally put the wrong fuel in your car you're not alone. At least 150,000 drivers put the wrong fuel in their car every year. That's one every three and a half minutes.
'Misfuelling' seems to be associated particularly with the recent growth in diesel car sales – modern diesels are so quiet it's easy to forget you're driving one
If you've put the wrong fuel in your car, don't turn on the ignition or start the engine .
Potential Damage
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Diesel fuel pumps operate on very fine tolerances and are lubricated by the fuel. Petrol in diesel acts as a solvent, reducing lubrication, and can cause damage to the pump through metal to metal contact. |
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Some fuel system seals can be affected by the compounds in petrol too. |
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The further the contaminated petrol goes in the system the more expensive the repair. In some cases it can be cheaper to fit a new engine! |
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Common rail (or HDi) diesel engines are particularly vulnerable – if fuel contaminated by pump wear debris gets as far as the common rail system you may have to replace the low and high-pressure fuel pumps, injectors, fuel rail, line filters and the fuel tank. |
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Many cars have a low-pressure electric pump in the tank which starts to work as soon as the ignition is switched on, circulating contaminated fuel through the pump and rail, so it's important not to turn the ignition on. |
Petrol in Diesel
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Don't turn on the ignition or start the car |
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If the car's still under warranty check with a dealer regarding their advice and correct remedial action – running with even a small amount of petrol in the tank might invalidate the warranty. |
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Some manufacturers advise that you should get seals and filters renewed even if the engine has not been run. |
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A small amount of incorrect fuel should not damage the engine as long as you have not started the car and top up fully with diesel. |
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If you've added more than 5 litres of petrol – Drain the tank and refill with diesel |
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If you've added less than 5 litres of petrol – Top up with diesel and run normally unless the manufacturer has advised otherwise |
Diesel in Petrol
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Don't turn on the ignition or start the car |
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This is less common because the standard diesel nozzle is bigger than the filler neck on modern petrol cars – you have to be pretty determined and patient to misfuel with diesel. |
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If the car is still under warranty check with a dealer regarding their advice and the correct remedial action. |
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A small amount of incorrect fuel should not damage the engine as long as you have not started the car top up fully with petrol. |
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If you've added more than 5 litres of diesel – Get the tank drained and don't run the engine. |
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If you've added less than 5 litres of diesel – the tank can be topped up with petrol and the car run normally unless the manufacturer has advised otherwise |
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has compiled this information to be used for educational purposes only
