How an engine’s fuel filter works

Fuel Filter Image

Not all cars have serviceable fuel filters. Most modern cars have filters as part of the fuel pump module in the gas tank, which makes replacing them an expensive business – if your filter is a separate entity count yourself lucky. On some models the filter is located in the engine bay. Haynes will be able to tell you where yours is.

The filter is designed to capture foreign particles from reaching the engine. These particles may have been introduced at the filling station, in the fuel, or could have come from the inside of the car’s fuel tank, especially if it’s an older car.

This task requires extensive experience, using specialist tools, and can take several hours, depending on your model.

Every car is different, so before you view the full instructions, find yours…

When to change your fuel filter

“The engine may stall, it’ll be difficult to start and you’re likely to have an engine fault light on the dashboard”

Consult your car’s manual to see when the fuel filter should be changed. Some manufacturers advise that no maintenance is required. In fact the only time you may need to change your fuel filter is when it’s blocked and is causing engine issues. This fuel starvation will cause the engine to stall, it may be difficult to start and you’re likely to have an engine fault light on the dashboard. A blocked filter may also damage the fuel pump, so it should be replaced as soon as possible.

You’ll also need to change the fuel filter if you’ve put the wrong fuel in your car’s tank. This will avoid contaminating the system once the tank, pipes and pump have been emptied, flushed and filled with the correct fuel.

The fuel system on a fuel-injected car is under high pressure, so you’ll need to depressurize it before you can remove the filter. Once it’s removed, check that the new one is identical and make sure you install it the right way round.

All cars are slightly different, so if it is time to change your fuel filter, use our before you begin checklist, and find your car for specific instructions.

How to change your fuel filter

This is a clip from a sample video. Find the full step-by-step task for your model.

A very brief summary of the task:

  1. Depressurize the fuel system by following Haynes’ procedures for your model 
  2. Remove the negative cable from your battery. Raise the car on jackstands. Locate the fuel filter
  3. Clean the pipes either side of the filter and remove the clamps or banjo fittings. Remove the filter and have rags to hand to mop up fuel
  4. Fit the new filter, using new washers if necessary, reconnect the battery and refit and fuses, if applicable

Why you should change your fuel filter

A dirty fuel filter will be full of contaminants. It’s important that these are kept from entering the engine because it risks fouling the fuel injectors and causing damage to the cylinders and pistons.

A clogged filter will also put the fuel pump under greater stress, and it could fail, leading to a potentially big repair bill.

Before you begin

Tools you will need

A comprehensive toolkit may be needed for this task, depending on your model

  • Floor jack (if necessary). Not your car’s emergency jack
  • Axle stands
  • Fuel pressure gauge with bleed-off valve/drain hose
  • Spanner set
  • Socket set
  • Pliers
  • Needle-nose pliers
  • Large adjustable pliers
  • Flat-bladed screwdriver
  • Phillips screwdriver
  • Rags
  • Power drill

Parts you may need

  • Filter
  • Seals

Every car is different, so before you view the full instructions, find yours…