How To Tell If Diesel Injectors Need Replacing?

The fuel injection system is an important part of any diesel engine. The fuel is pressurized and injected into compressed air in the combustion chamber via this system. Feeding fuel to the injectors, regulating the fuel supply, modifying the injection time, and atomizing the fuel are all operations of a fuel injection system.

The proper amount of fuel, at the right time, in the right condition for combustion, must be delivered.

Fuel injectors help enhance fuel efficiency, reduce the need for fuel system maintenance, and keep emissions cleaner. A diesel fuel injector has an average lifespan of 100,000 kilometers. The nozzle and the injector body are the two primary elements of a standard fuel injector. If either of these components becomes clogged or destroyed, the vehicle’s overall performance is jeopardized.

  • Uneven idling or difficulty starting the car. The engine cranks, but it won’t start unless you crank it hard enough. On idle, the engine uses a variety of rev levels.
  • Misfire. A full diagnostic of a vehicle that is misfiring on ignition entails determining which component of the combustion process is missing. This is caused by either a lack of fuel injection or a lack of combustion chamber heat in a diesel engine. One of the cylinders’ fuel charge fails to ignite, or the fuel supply to the ignition system is insufficient.
  • There’s a strong odor of gasoline. The scent of diesel within the cabin indicates that there is a leak. This could be caused by a malfunctioning injector that allows fuel to leak out while it isn’t in use.
  • Emissions are filthy. Filters that are clogged and deposits on injectors create an uneven or partial fuel burn, resulting in a polluted environment around the exhaust and the discharge of white smoke from the exhaust pipe.
  • Fuel consumption has increased, while miles per gallon has decreased. Faulty injectors waste more fuel and have a direct impact on the performance and efficiency of your vehicle.

Clean fuel injectors are essential for your diesel engine to run at its best. Any of the following signs could suggest an issue with your fuel injectors, which should not be overlooked. Injectors that are unclean, clogged, or leaky are examples of this. If you’ve driven your car for more than 100,000 miles without replacing the fuel injectors, it’s time to have them looked at by a specialist.

How do you know when to replace diesel injectors?

Wear on diesel fuel injectors

  • Power that fluctuates. If your vehicle’s engine revs up and down or your RPM gauge goes up and down, it’s possible your fuel injector needs to be cleaned.

How do you check diesel injectors?

Your diesel engine’s fuel injectors are critical to the vehicle’s functionality. When they’re working properly, you’ll have a smooth-riding car with all the power you need to get around and get things done. Your fuel injectors deliver the fuel efficiency you expect from your car and help keep your engine’s emissions safe when they’re performing at their best. We’ll show you how to test your fuel injectors in this article.


The method you use will be determined by the type of fuel injection in your car. Start with these instructions if you have a throttle body injection (TBI) system:

  • That injector is fine if the fuel is partially atomized and spraying in a v-shaped pattern.
  • The injector is clogged if the fuel spray is fragmented or solid. You can either use a fuel cleaner additive to unclog it or take it to your repair.
  • If the injector isn’t spraying fuel, it’s either entirely blocked, has a defective injector, or something else is wrong, such as the fuel pump or fuel filter. If this is the case, go to the next stages.


The following steps apply to a clogged or non-functioning TBI system injector, as well as automobiles with electronic fuel injection (EFI) systems. Here’s where your long screwdriver or metal rod comes in handy.

  • Lean your head carefully toward the screwdriver’s or rod’s far end. Make sure you’re wearing your safety equipment. You should be able to hear a clicking sound if the injector is working properly.
  • Repeat the screwdriver test on each injector, noting which ones don’t seem to be clicking.
  • Turn the engine off and on the batteries to turn on the lights, radio, and other gadgets but not the engine.
  • Connect the negative terminal of your vehicle’s battery to the clip of the automotive test light. Then, with the test light’s pointed tip, contact the small portion of exposed wire on the fuel injector connector. If the injector is working properly, the test light should illuminate.
  • Repeat the test light procedure for each injector, noting which ones do not illuminate.

How often do diesel fuel injectors need to be replaced?

Diesel fuel injectors should be replaced every 150,000 to 250,000 miles as a matter of thumb. Every 50,000 miles, they should be inspected by a professional for optimal operation.

Obviously, this will vary depending on how well you maintain your engine. factors such as:

Is it worth replacing fuel injectors?

If the problem is caused by the fuel injectors, you have two choices: replace them or flush them.

A replacement is usually the best solution. However, there are times when a flush is all that is required.

When fuel injectors fail, it’s usually because they’ve become blocked by contaminants in the gasoline.

Flushing the fuel injectors is a good diagnostic step, but it could also be a solution if the problem is found to be caused by debris in the injectors.

This is great news because a fuel injector clean is much less expensive than replacing the injectors.


The cost of changing fuel injectors is determined by a variety of parameters, the most important of which are the number of cylinders, car model, and engine.

It is recommended that you replace all of the fuel injectors at the same time. It will save you money on labor while also ensuring that the engine does not run harsh.

One fuel injector will cost between $100 and $300 for most automobiles.

Multiply it by the number of cylinders in your automobile to get an estimate of how much it will cost.

Depending on the automobile model and engine size, the overall cost can potentially approach $2000.

The labor rate is also affected by where you park your car and where you reside. A fuel injector replacement should take 1 to 2 hours in most cases.

Flushing the injectors is also an excellent alternative for this reason. If you do it yourself, a flush can cost as little as $10, or $50 to $70 if you hire a professional.

What are the symptoms of fuel injector problems?

Knowing how sophisticated your fuel injection system is, it’s easy to see how bad or dirty fuel injectors may cause havoc with your engine!

The Engine Misfires

Fuel injectors that are dirty can cause your vehicle’s engine to misfire. This condition causes the motor to splutter, causing vibrations throughout the vehicle. Misfires can occur when a faulty fuel injector disrupts the precise balance of fuel and air entering the engine.

Idling Gets Rough

When you’re stopped at a stop sign or stuck in traffic, does your car splutter and shake? It’s not like you’re riding a bucking bronco. It’s alerting you to the possibility of clogged gasoline injectors at work.

Even when your foot is off the pedal, “rough idling” is characterized by variable revolutions per minute (RPMs). Engine stalling – a sudden drop in RPMs and engine noise that feels like running out of gas on a hill — is frequently associated with rough idling.

Rough idling and engine stalling can be caused by a variety of issues, including dirty fuel injectors. Come in for a Complete Vehicle Inspection if you detect any of these problems in your vehicle. Our professional technicians will diagnose the issue and, if necessary, recommend a fuel system cleaning.

Your Gas Mileage Tanks

Fuel injectors that work well assist your car get the gas mileage that manufacturers advertise. While a variety of engine problems may force you to visit your local gas station more frequently, poor gas mileage could indicate a problem with your fuel injectors.

The RPM Needle Starts to Dance

In most cases, you have control over what your car’s dash gauges do. The gas needle moves from “F” to “E” when you drive a lot. The speedometer changes from “0” to “60” as you accelerate.

What are the effects of unclean fuel injectors? They can cause the tachometer needle — the gauge that shows the vehicle’s RPM — to move in an unpredictable manner. When your car isn’t changing gears, the needle may move without warning, indicating changes in RPM.

Your Car Won’t Start

Fuel injectors are responsible for delivering gas to the correct cylinders. That is the first task. And if Job #1 isn’t completed, your engine won’t obtain the vital combination of oxygen and fuel it requires. When the air-to-fuel ratio in your engine is off, your engine may not be able to achieve the combustion it requires to run.

Fuel injector problems are uncommon, but they can cause engine failure and prevent your car from starting. It’s also possible that your car won’t start because you, well, neglected to fill it up with gas. (It occurs to everyone!) Unfortunately, running out of gas can also cause problems with the fuel injectors.

What are the symptoms of a bad fuel injector?

Depending on how badly the Fuel Injector is damaged, the symptoms will vary. However, symptoms such as engine detonation or knocking, smoke from the tail pipe, bucking and surging under throttle loads, rough engine performance or poor automobile performance in general, failed emissions, starting troubles, a poor idling, greater fuel consumption, and so on will most likely be present. Understanding and managing all of this is critical, so try to keep it in mind as much as possible. Keep track of the symptoms and, if there are any, deal with the situation. At the end of the day, you should be alright.

How much does it cost to replace a fuel injector?

It is not inexpensive to replace a fuel injector. It depends on where you reside, what brand you want to use, and where you want to install it. However, you should budget up to $350. The parts themselves are only worth up to $200, thus the remainder of the cost will be installation and labor. You must ensure that the fuel injector is properly replaced. It’ll never be easy to replace a bad injector on your own, so always hire a professional. Even if you want to save money, hiring an expert is still an excellent option. You may still learn how to clean gasoline injectors to extend their lifespan. You can even buy a cleaning for your fuel injectors. But, when it comes to replacements, why not use experts?

How do you know when to replace a fuel injector?

If the fuel injector isn’t working, the problems and symptoms listed will let you know. However, multiple tests have found that the Fuel Injector can survive anywhere from 50 to 100 thousand kilometers. Sometimes even a little more, depending on the circumstances. It’s crucial to take it to a mechanic to see if it needs to be changed. It’s possible that you’ll need to repair it before you reach 50k miles because it’s damaged.

We recommend that you take your time and make sure that your car is properly maintained on a regular basis. The better the results, the faster you can accomplish it. Take your time and make sure you’re concentrating on value and outcomes. You will not be disappointed if you choose the best replacement service!

What makes diesel injectors fail?

Excess wear, abrasion, and deposits, according to Afton Chemical’s North American Marketing Manager David Cleaver, are three significant causes of injector failure linked to the qualities of the fuel itself. Excessive wear is one cause of injector failure.