BREAKDOWN COVER INSURANCE FINANCIAL SERVICES BUY A CAR DRIVING TRAVEL Sign in Member benefits Shop Business Newsroom Home Breakdown cover Breakdown advice Wrong fuel advice Filled with the wrong fuel? Don't turn on the ignition or start the engine. Call 0800 072 7420 or 0121 535 7479 for help If you've accidently put the wrong fuel in your car, don't turn on the ignition or start the engine. This will circulate the contaminated fuel and increase the risk of expensive damage. You wouldn't be alone. At least 150,000 drivers put the wrong fuel in their car every year. That's one every three-and-a-half minutes. It could be a result of being new to the vehicle or simply being distracted while filling up. Do you need immediate help? Call 0800 072 7420 or 0121 535 7479. 'Misfuelling' seems to be associated particularly with the growth in diesel car sales. Modern diesels are so quiet it's easy to forget you're driving one, particularly if it's a second family car or hire car. Potential damage Diesel fuel pumps operate on very fine tolerances and at very high pressures – modern systems run at between 350 and 1600 bar) – 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. Metal particles from the damaged pump can be deposited in the fuel causing further damage to the rest of the fuel system. Some fuel system seals can be affected by the compounds in petrol too. The further the contaminated fuel goes in the system the more expensive the repair. In some cases it can be cheaper to fit a new engine! 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. Gasoline Direct Injection (GDI) petrol engines are particularly susceptible to damage too. 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 Don't turn on the ignition or start the car In line with car manufacturers' recommendations, AA advice is that any diesel fuel contaminated with petrol should be removed from the tank and replaced with clean fuel before the ignition is turned on and the car started. Diesel in petrol Don't turn on the ignition or start the car This is less common because the standard diesel nozzle is bigger than the filler neck on modern petrol cars. In line with car manufacturers' recommendations, AA advice is that any petrol contaminated with diesel should be removed from the tank and replaced with clean fuel before the ignition is turned on and the car started. AA Fuel AssistSM Fuel Assist is a specialist roadside service that drains, flushes and replenishes vehicle fuel systems on the spot, saving you time, money and inconvenience. Fuel Assist is available to the general public as well as to AA Members. We will attend any vehicle providing the Fuel Assist van has enough capacity in its tanks. (Updated 22 July 2014) Related advice & information AA Fuel Assist What to do if you breakdown Fuel price reports Top ten breakdowns Common winter breakdowns Change a wheel safely Warning lights Regular vehicle checks More motoring advice Buying a car Breakdown advice Driving abroad Any assistance Flat battery? Wrong fuel? Top ten breakdown causes Breakdown Breakdown cover European breakdown Breakdown repair cover Motorbike breakdown Business breakdown Insurance Car insurance Home insurance Travel insurance Life insurance Business insurance Home cover Boiler and heating cover Home emergencies Home membership One-off repairs Cover for landlords Finance Savings Loans Credit cards Travel currency cards Wills Driving Driving school Tyres Windscreen repairs Car batteries Travel European breakdown IDP driving permits Book a hotel Car hire Route planner Contact us Investor relations Jobs Newsroom AA Charitable Trust AA history Accessibility Privacy policy Cookies Terms & conditions © Automobile Association Developments Ltd 2014