Do Your Car’s Fuel Injectors Need Checking?

Be honest – when was the last time you thought about your car’s fuel injectors? Unless you’re a mechanic, it’s not really something that comes up in daily life. It’s certainly not something that, for most UK drivers, finds itself at the top of the maintenance checklist – until, of course, there’s a problem with them!

The quick answer to the title of this blog is that, yes, fuel injectors do need checking – but they’re not something you usually need to obsess over. Let’s look at what fuel injectors are, how they work, signs they may need attention, and which options are available for keeping them clean.

Fuel-using engines are known as “Internal Combustion Engines”, because they burn a particular fuel in order to provide power. Think of them as very advanced forms of a wood-fired turbine (you can learn about how engines actually work here). Now, modern engines have become so fine-tuned that you can’t have fuel thrown into the fire (so to speak) at random. In order for it to work effectively, you need to put precise amounts of fuel into the combustion chambers at precise times.

This, essentially, maximises performance, fuel economy, and emissions control. Let’s look at some signs that your fuel injectors could need attention.

Dirty or failing injectors can cause a variety of symptoms. If you’ve noticed any of the following issues, it could be time to give them some attention:

• Rough idling or misfiring – which makes the car feel shaky when stationary.
• Poor acceleration – sluggish response when pressing the accelerator.
• Increased fuel consumption – fewer miles per gallon than usual.
• Strong fuel smell – excess fuel may be escaping unburnt.
• Difficulty starting – especially when the engine is warm.
• Excessive exhaust smoke – often dark or black.

If you’ve spotted one or more of these symptoms, your injectors may be clogged with carbon deposits. But it’s important to take a holistic view of the car’s components. You need to consider the whole combustion system in order to get a good view of possible culprits (which is why it can often be worth leaving it to an expert). For example, difficulty starting and rough idling could also be battery or exhaust issues.

When you combust any fuel, you convert parts of it to heat energy – and parts of it are left behind (think about the ash left after a campfire). Now, modern engine fuel (especially more recent petrol formulations) is designed to burn very efficiently and leave as few deposits or impurities as possible, but it’s not perfect.

Over time, these small carbon deposits – as well as other impurities – build up inside your injectors simply due to the way that engines work. What’s more, short journeys (i.e. journeys under around 10-15 minutes) don’t let the engine reach the optimal temperature to burn the fuel more cleanly – which means you get more residue build-up. Add in the reality of stop-start driving in the traffic of most towns and cities, and it’s no wonder that fuel injectors need a bit of a helping hand every now and then!

Some drivers consider tackling injector cleaning themselves. The most common DIY approach is to use a fuel additive – a specially formulated cleaner that you pour into your fuel tank. As you drive, it circulates through your system, helping to break down carbon deposits.

The pros are that fuel additives are easy to use, affordable, and can be effective as part of regular maintenance. But the downside is that they usually won’t fix severely clogged injectors, and the results vary depending on your driving style and the condition of the injectors in the first place.

The other option is to go for a professional cleaning. Technicians like the experts at our centres can carry out a more thorough engine cleaning service, using specialist equipment and solutions designed to flush out deposits more effectively than DIY products.

The main upside to a professional clean – other than you not having to take on the stress of doing it yourself – is that we can deep clean heavily clogged injectors, and a professional clean is likely to restore performance and fuel economy more quickly than waiting for off-the-shelf fuel additives to work their way through your engine system.

The only downsides are that professional injector cleaning comes at a slightly higher cost than DIY additives, and requires booking in for a service.

Unlike with other checks like tyre tread depth checks or oil changes, there isn’t a set mileage for injector maintenance, as it depends on your car, driving style, and fuel quality. However, as a general rule:

• Consider using a fuel additive like Cataclean every few months, or about a month before an MOT.
• Book a professional cleaning service if you notice persistent issues like misfiring, poor performance, or high fuel consumption.
• Ask your technician to check your injectors as part of your regular service – prevention is always better than cure.

For more tips on maintenance schedules, check out our blog on how often you should service your car.

To summarise, maintaining clean injectors certainly provides performance benefits, but it isn’t just about performance – it’s about saving money, and reducing your environmental impact too.

• Better fuel economy – spend less at the pump.
• Reduced emissions – cleaner air and a greater chance of passing your MOT emissions test.
• Improved reliability – fewer misfires or breakdowns.
• Longer lifespan for your engine – less strain on internal components.

In short, keeping your injectors clean is an investment in both your car’s health and your wallet.