Fuel Filters: Everything You Need To Know

Fuel Filters: Everything You Need To Know

Whilst very small, and hidden away out of sight, the fuel filter is a component present in every petrol or diesel-engined car, which contributes a significant amount to the smooth running and reliability of modern vehicles.  

This article will go into the ins and outs of fuel filters, including how they work, when to change them, how much a replacement fuel filter costs and more. 

What do Fuel Filters do?  

It may seem self-explanatory, but it's important to understand the role of fuel filtration in modern cars, which is more vital than ever.  

Once refined from crude oil, the petrol or diesel may well travel thousands of miles to get to your tank. During this time it will travel through ageing pipes, tanks and valves.  

All this results in an end product that is often quite far from perfect, with sediment, dirt and other impurities being present. Due to the traditional usage and production diesel tends to contain more impurities than petrol.  

How much do fuel filters cost to replace? 

The average cost to replace a fuel filter is £105, with prices ranging from £70 on older/simpler cars, and up to £150 on premium/luxury brands. 

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How do fuel filters work? 

Often fitted in line with the fuel line, between the fuel tank and the fuel system in the engine bay, all fuel flow is routed through the filter, and subsequently through the filter elements. Any pieces of debris or dirt are captured in the filter elements, preventing them from entering the fuel system or engine.  

What are the two types of fuel filter? 

Almost all fuel filters fall into one of two categories; inline and cartridge.  

An inline filter is a plastic or metal unit with tube connectors in each end, a flexible fuel hose is connected to these, with the fuel line passing through the unit from one end to another.  

Cartridge-type filters use a plastic housing with a removable ‘bowl’, inside the bowl sits the filter element. To replace the filter element, the bowl is unscrewed, the filter replaced and the bowl re-attached.  

There is no inherent benefit to either type, and the type of replacement filter you need to buy will depend entirely on the manufacturer’s design - it’s important to note the two types are not interchangeable - most garages or auto parts stores will be able to search up which part you need.

How often should you replace a fuel filter? 

Fuel filters should be replaced every 30,000 miles or two years of use, but check your car’s manual for more precise information. 

As the fuel filter is not an overly expensive service item, it’s not worth neglecting to change it as part of your bi-yearly service schedule.  

Split the cost of car repairs into monthly payments at 1000s of garages and dealerships. 

Is a fuel filter included in a service? 

Major services will typically include a fuel filter as standard. While the car is on a lift, it would be a relatively simple job for a mechanic to replace it.  

For more information on what services include, check out our guide to car services and what they include.

Why do fuel filters need to be replaced? 

Over time the elements become fully saturated with debris, and will both allow some contaminants to pass through, as well as restricting fuel flow to the engine, causing starting and running issues.  

Some cars have larger filters that can last longer between changes, but even these will need replacing after they’ve been functioning as intended for a long period of time. 

What happens if you don't change your fuel filter? 

Naturally, a good uninhibited supply of fuel is vital to an internal combustion engine, but there are various problems that can indicate you may benefit from replacing your fuel filter: 

  • Starting issues 
  • Running issues - especially at high engine RPM 
  • Stuttering under load or on hills 
  • Fuel pump noise or wear 

Will a new fuel filter improve performance? 

Yes, if your fuel filter is very old, there is a good chance a replacement one will improve engine performance. In modern cars, engine fueling is adjusted to take account for the quality and pressure of the fuel supply. A new fuel filter will allow a better fuel flow to the engine, meaning improved performance may be noticed. 

Can I change my fuel filter myself? 

Changing a fuel filter is a relatively simple process. As many inline filters are near the fuel tank, you’ll likely need to get underneath the car - which requires extreme caution and attention. 

If you have the space, tools and expertise to safely jack up and support your vehicle, the only other tools needed are basic hand tools including screwdrivers and pliers to pull off the fuel lines. 

If you are at all unsure about jacking and supporting your vehicle, and your fuel filter is underneath the car, do not attempt to change it yourself, we’d suggest including it as part of your service via one of our approved service partners. 

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