Wrong fuel glossary
The words that come up when you have put the wrong fuel in — from misfuelling itself to the parts of the fuel system it can damage — defined in plain English. If you have just put the wrong fuel in, skip the reading: leave the engine off and call 01295 380724.
Wrong fuel glossary, A to Z
- Misfuelling
Putting the wrong fuel, or a fluid that is not fuel, into a vehicle's tank. The common cases are petrol in a diesel and diesel in a petrol.
- Fuel drain
Pumping the contaminated contents out of the tank, flushing the fuel lines and refilling with the right fuel, usually where the vehicle is parked.
- Fuel flush
Running clean fuel through the lines, and sometimes the filter, after a drain to clear what is left behind.
- Petrol in a diesel
The most common misfuel. Petrol thins the diesel and strips the lubrication the high-pressure pump depends on.
- Diesel in a petrol
Less common, because a diesel nozzle is wider than a petrol filler. Diesel does not ignite properly on a spark, so the engine misfires or will not start.
- AdBlue
A solution of 32.5% urea in de-ionised water, injected into a diesel's exhaust to cut nitrogen oxides. Its generic name is diesel exhaust fluid (DEF).
- SCR (selective catalytic reduction)
The exhaust system that uses AdBlue to turn nitrogen oxides into nitrogen and water. Fuel in the AdBlue tank can damage its pump and injector.
- E10
Petrol containing up to 10% renewable ethanol, the standard grade at pumps in Great Britain since September 2021.
- E5
Petrol containing up to 5% ethanol, sold as the super grade and kept for older vehicles that are not compatible with E10.
- Red diesel
Gas oil marked with dye and charged at a lower rate of duty for permitted uses such as agriculture. Using it in a road vehicle is an offence.
- High-pressure fuel pump
The pump that feeds a modern diesel's injectors at very high pressure. It is lubricated by the diesel passing through it, which is why petrol damages it.
- Injector
The valve that sprays fuel into the engine. Damaged injectors are the expensive end of a misfuel.
- Lift pump
The in-tank pump that moves fuel towards the engine. On many cars it runs as soon as the ignition is switched on, which is why even turning the key matters.
- Limp mode
A protective mode in which the engine management limits power after detecting a fault; contaminated fuel is a common trigger.
- Call-out fee
The charge for a technician to attend. Here it is £89 to £199 in the UK; the drain itself is priced separately at £199 to £1,999, and both are quoted on the phone before anyone travels.
Background: Misfuelling on Wikipedia.
Sister data: Wrong Fuel Drain publishes the fuel-drain coverage dataset (catalogue: DCAT). Each dataset lives on one site only.