How much does it cost to repair a diesel injector?

Properly functioning fuel injectors are essential in a diesel engine, causing a few different issues when they fail or deteriorate, with a large repair bill often being the most notable!

In this article, we’ll discuss some common symptoms of injector issues, how they are usually fixed, and typical costs for repair.

Diesel injector repair costs

Replacing a single faulty diesel injector typically costs between £300 and £900. If replacing all 4, expect the cost to be north of £800, and reach £2,000+ if they are difficult to remove.

Labour charges generally make up a significant proportion of the cost to replace diesel injectors, which can vary wildly depending on how easily the old injectors can be removed from the engine.

Aftermarket (non-genuine) injectors typically cost between £90 and £150 each, whereas genuine ones will often set you back £300 each or more, depending on the make.

For help covering a large repair bill, consider Bumper's car repair finance to split the cost.

What is a diesel injector?

Diesel cars use injectors to add fuel to the engine’s cylinders. They are specifically needed in diesel engines to overcome the extremely high pressures needed inside the engine, to make diesel burn efficiently.

Diesel injectors act as small and precise valves to allow fuel from the high-pressure fuel system through, whilst also atomising the fuel into a mist, allowing for a more efficient burn.

How do diesel injectors go bad?

The orifice from which the diesel is sprayed is roughly the same diameter as a human hair, and as such is very susceptible to clogging if the fuel system is not properly maintained.

Multiple stages of filtration are used to prevent this issue, but over time, particles and sludge can build up, affecting the spray pattern and volume. This is one of the reasons it is important to follow servicing schedules, including replacing fuel filters.

Another common failure mode is when the rubber seals that keep the diesel fuel contained within the injector housing fail, causing leaks and a lack of fuel pressure injected into the cylinder.

Should you replace all diesel injectors at once?

It is good practice to replace all injectors at once, but is not always necessary. In many cases, the cause of the failed injector has an impact, as well as the age of the vehicle.

If the car and engine is old, but is likely to give prolonged service, it’s best to change all the injectors. This is because a failure due to general wear and age indicates future failures are likely.

However, if the car is destined for the scrap heap in a year or two, it’s probably not worth replacing them all.

Can you drive with bad diesel injectors?

It is highly recommended to replace any bad diesel injectors as soon as possible, without continuing to drive the car. A faulty diesel injector will cause very poor running, starting and emissions levels.

What’s more, prolonged use may cause more significant problems with the engine, including severe diesel leaks, and on some occasions, diesel even getting into the engine oil, which will be very bad for your engine’s health.

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Author - Joseph Law

Joseph has been writing about cars for over eight years and writing for Bumper for over three, blending his passion for automobiles with a talent for storytelling.

Joseph has written about engineering and cars for Autozilla, Komaspec, and several engineering manufacturers. When he's not writing or tinkering with one of his cars, Joseph dreams of owning an Alfa Romeo 33 Stradale.