Home Diagnosis and TroubleshootingFuel Systems Dirty Fuel Injectors – How To Clean Them Without Removal?

Dirty Fuel Injectors – How To Clean Them Without Removal?

by Jordan Harris
Dirty Fuel Injectors

Have your engine started to misfire and threw the check engine light on? And you are scratching your head of what could be the problem with your car? And you think that you have dirty fuel injectors? If that’s the case, then you are at the right place because there will be a lot to cover on this topic.

Having a problem like this with the injectors can be a frustrating thing to deal with. Why I’m saying this? Well, this is actually the case because a faulty injector can hurt the performance of your vehicle. With bad injectors, the performance of the cars will drop significantly.

When the injector isn’t working well, it could create a bad spray pattern that will make the cylinder misfire. Also, if an injector isn’t working well, it could cause the engine to show the check engine light and in this case, you will definitely need to put up your sleeves and start messing up with diagnostics tools. Namely, the OBD2 scanner. But more on this, we are going to elaborate later on when we will discuss the systems.

First, let’s learn more about fuel injection systems and learn the most common ones. Then we will cover the fuel injectors and learn how they work. After that, we will focus on dirty fuel injectors. We will learn the symptoms, the diagnosing, and the testing phases. How to clean them and the costs involved in cleaning and replacing these components. So, if you want to learn more, follow along.

Fuel Injection Systems – Port Vs Direct Injection

Now before we dive into some dirty fuel injectors symptoms and learn more about why they could fail. Let’s start with the basics and learn more about the types of fuel injection that are common nowadays in cars.

Knowing the types of injections will help you determine what type of injectors you have. Since not all injectors are the same. There are cheap ones and there are expensive ones.

So, let’s elaborate more on the two types of fuel injection that are common nowadays. We will not discuss carburetors since this article isn’t about carbs. We focus only on fuel injection in this article.

The first type of injection that we are going to cover is the port injection. Port injection is one of the most common types and a ton of cars are using it. How you can tell that you use port injection?

Dirty Fuel Injectors

Well, it is rather easy. Port injection cars do not have a secondary high-pressure fuel pump. Also, their injectors are low pressure which means that the fuel is not that atomized as in the following type that we are going to cover.

And on top of that, the injectors on port injection cars are cheaper to purchase and replace. The fuel is sprayed in the intake ports of the engine. Thus the name, port injection.

Nevertheless, the second type that you need to be concerned about is direct injection. Nowadays all diesel engines, as well as turbocharged gas engines are mostly direct injection.

Direct injection is rather complex. It includes a high-pressure fuel pump as well as more complex injectors that are placed vertically in the engine. Not in the intake ports as the previous type. Making these dirty fuel injectors a lot more expensive to replace.

What Are Fuel Injectors And How They Work?

Now before we learn the symptoms of dirty fuel injectors, let’s learn more about what are these components and how they work. Knowing this will be really beneficial to understand why they fail in the first place.

As we already explained, there are two systems. Multi-port injection and direct injection types of systems of injecting fuel.

When it comes to the injectors themselves, they both function on the same principles. The only difference is that direct injection injectors are far superior in construction and also they are heavy-duty components since the pressure inside them is enormous. This is why they are often made out of steel and the regular port injectors are made out of plastic.

When it comes to the fuel injector diagram. We can say that in each injector there are solenoid components and the fuel injector assembly.

The fuel injector mechanism is in charge of distributing the fuel into the cylinder. This mechanism consists of the filter which is on top, then in the middle, there is the valve spring, after the spring there is the plunger and at the very top is the spray tip which sprays the atomized fuel.

While on the other hand, the solenoid is in charge to regulate when the injector will open and deliver the fuel. So, when the computer gets the information it will direct the solenoid to open. And when the solenoid opens it will allow fuel to be injected.

The solenoid simply follows the orders of the PCM, which is the car computer. Sometimes though, the solenoid can stop working and the injector to stuck open or closed and cause a problem. Another problem is the dirty fuel injectors that we are going to discuss next.

Dirty Fuel Injectors Symptoms

Now as we cleared the basics and learned what injectors are doing in the internal combustion engine. Let’s now focus more on the dirty fuel injector symptoms.

Knowing these fuel injector symptoms will really help you out when determining what could be the cause of your problem and if you really indeed have dirty fuel injectors on your car. So, let’s cover them briefly.

1. Check Engine Light

The first and most common symptom of dirty fuel injectors is the check engine light. The check engine light will be triggered when some of these components are not functioning as they should be.

The codes for the fuel injectors start with P0200. Then this number increases as the cylinder numbers increase. So, the code for cylinder number 1 will be P0201, for cylinder 2 the code will be P0201, and so on. You get the point.

Dirty Fuel Injectors

Also, whenever there is a problem with the injectors, there also will be some codes that indicate misfires. Such as P0300 which refers to a random misfire. Or for a specific cylinder code such as P0302 which indicates a misfire on cylinder number 2.

These codes are a good lead for you when it comes to determining if this is a problem with the injectors and if you have dirty fuel injectors. Now let’s move to the next symptom.

2. Rough Engine Idle

The next symptom that we would like to address when it comes to dirty fuel injectors is the rough engine idle. The engine will for sure going to run rough whenever there is a problem with the injectors.

You will notice how the engine shakes more than usual and also the work of the engine will be odd, the RPM will rise and drop.

This means that the engine will be inconsistent in its work. Which is a clear sign that something is going on inside of the engine and this needs to be checked promptly before the problem gets bigger. This is why cleaning dirty fuel injectors can save your life in situations like this. But more on that later on in the article.

3. Engine Misfires

The next symptom that we are going to cover when it comes to dirty fuel injectors is the engine misfires. Whenever the engine is having a problem with the injectors, the misfires are one of the most common symptoms.

We hinted at this previously in the check engine light section. What is good is that whenever your engine misfires, in other words when the engine runs poorly and have premature or delayed combustion, it will throw the check engine light.

Dirty Fuel Injectors

And based on these clues, you can search for your problem. So, if you get a P0305 code, it means that cylinder number 5 has some kind of misfire problem and this could be attributed to a bad spark plug or dirty fuel injectors.

4. Engine Hesitation And Surging

The next symptom of dirty fuel injectors that we are going to cover is the situation when you have problems like engine hesitation and surging. So, why this will be the case?

Well, this will be the case if you have an unbalanced spray pattern. Imagine that your fuel injector is spraying inconsistently.

At one point you have no fuel, and then you have too much fuel all of a sudden. This will result in engine hesitation and surging.

You will press on the gas and nothing happens. Then suddenly the engine is surging and the car lurches forward. A clear symptom of a problem with dirty fuel injectors or problem with other fuel delivery components like the fuel filter or fuel pump.

5. Poor Fuel Economy

The next symptom that we would like to cover when it comes to dirty fuel injectors is poor fuel economy.

When you have injectors that are not performing as they should and are leaking fuel all the time. The result will be a significant drop in the fuel efficiency of your vehicles.

And you are going to notice this, your visits to the gas station will be more and more frequent than they were before.

MPG engine economy efficiency

So, if you notice that the fuel economy of your car has dropped, it is a good idea to check out the fuel system and see how these injectors perform on your vehicle. This way you will be sure what could be causing the problem and how to tackle it quickly before it gets bigger and possibly damages other components like the catalytic converter, spark plugs, etc.

All these components are affected when the car is running rich and drinking a ton of gasoline. And frankly, they are really expensive to fix. That’s why clean the dirty fuel injectors and solve your problem before this issue becomes too expensive.

6. Smell Of Fuel

Another very common symptom of bad or dirty fuel injectors is the situation when you experience a smell of fuel inside the cabin. So, why is this the case?

This is the case because the injectors are probably clogged up and not allowing the fuel to pass through. So, if the injector has too much pressure inside, it will eventually fail and will start to leak fuel.

This will be nothing significant, only a few drops coming from the fuel rail. But still, a really serious problem because it can lead to a fire. Mainly because temperatures in the engine get really high and if you do not sort this problem, you definitely are taking your chances of causing a fire because of dirty fuel injectors.

7. Failed Emissions Testing

And the last symptom of dirty fuel injectors that we are going to cover is the situation when you fail your emissions.

Whenever there are dirty fuel injectors, it is expected that this will affect your emissions. It could prevent some fuel from flowing which will result in poor burning of gasoline and this could be a trigger.

Increased Emissions

Since the car will not produce the required amount of gases for this model. Or it could produce too many gases if the injectors are leaking fuel all the time. So, if you live in a state that is strict when it comes to these things, they could easily fail your emissions testing and tell you to fix the problem first and come back later after you repaired the problem with the dirty fuel injectors.

But how you can diagnose dirty fuel injectors? Well, that’s what we are going to cover next.

Diagnosing Dirty Fuel Injectors

Now let’s learn how you can diagnose dirty fuel injectors. This will be useful for you when it comes to figuring this problem out. So, how you can do these diagnostics?

Well, the first thing you need to look at is to see if you have leaks from the top of the fuel rail. Check all the injectors and see if they smell like gasoline.

Then if everything seems fine, you might want to get an OBD2 scanner and let the scanner scan for codes.

If you get codes that start from P0200 or P0300 it could mean that there is a problem with some of the injectors. The first set of codes that range from P0200 to P0208 indicate issues with the injectors while the P0300 to P0308 indicate engine misfires.

So, if you get codes specific for cylinder then this is good news. Just mark the bad injector and swap it with a good injector.

Then you can just erase the codes and scan the car again. If the problem moves to a different cylinder, congratulations, you found the problematic injector. Things are really easy to tackle when you use a little bit of ingenuity.

But enough on testing fuel injectors and diagnosing the problem. Let’s now see what we can do about cleaning the dirty fuel injectors on your car. How you can tackle this problem? Let’s elaborate more on that next.

How To Clean Injectors DIY?

How you can clean dirty fuel injectors? Well, there are two methods of performing this task. One of them is simple, while the other method requires a little bit of skill.

The first method will require using a fuel additive. There are special fuel additives out there like the one by Seafoam. They are specifically designed to tackle clogged fuel injectors and clean them really well.

The only thing you will need to do in this case will be to pour this additive into the gas tank and run the engine like this for a while. This solution will get all the debris out of the injectors and hopefully will restore them to normal.

The second method will require a bit of ingenuity. For this method which only works with gas cars you will need to disconnect the fuse for the fuel pump, then disconnect the fuel line hose that goes to the fuel rail.

Then directly to the fuel rail, you will need to attach a carb cleaner can. For this, you will need a hose that will fit the line, and a little bit of glue to improvise this fitting. How it’s done can check in the video above.

The important thing when you connect this carburetor cleaner can, your engine will only run on carb cleaner. So, you should be constantly spraying this carb cleaner until you eventually be left without a carb cleaner. And cross your fingers that you solved the problem and the injector is cleaned and you don’t have dirty fuel injectors anymore.

Fuel Injection Service Cost

If you are not experienced with solving problems like the one with the dirty fuel injectors and you are looking for an easy way around this issue of dirty fuel injectors, your best bet would be to look for a fuel injection service.

There are a ton of shops that offer these services. Just browse online for fuel injection service near me and there would be a ton of places that will offer you this service. So, don’t be scared and look for someone to help you out.

Fuel Injector Replacement Cost

What is bad with these injectors is that you cannot replace only one. When you replace one, the other will end up not working. Which is the case in most direct injection cars.

This is the case because the computer is programmed to work with these injectors. So, when you change one of them it will cause all of them to malfunction.

On some cars, you can replace only one, especially on older vehicles produced before 2007. The cost of a new part is about $150. Not crazy expensive. Still, first, make sure that you can replace only one injector. That’s why when it comes to dirty fuel injectors it is recommended to try to clean them first.

Driving With Bad Fuel Injector

Technically you can drive with bad or dirty fuel injectors. But for how long that depends on the extent of the damage to the injectors.

If they perform really badly, then you can expect too many different symptoms that will make your driving experience really annoying, this is why you need to replace them before the problem becomes bigger.

Facts about Fuel Injector Clogging and Diagnostics:

  • Clogged fuel injectors prevent fuel flow, causing rough engine performance, bad emissions, and poor fuel consumption.
  • Symptoms of clogged fuel injectors include rough engine performance, cylinder misfires, loss of power, and difficulty starting.
  • Diagnosing clogged or dead fuel injectors is difficult, as it mimics problems with spark plugs, coils, or other electrical components.
  • To diagnose clogged fuel injectors, perform tests such as checking for warm exhaust manifolds, inspecting the injector connector, checking for power and resistance with an ohm meter or Noid light, and using a stethoscope to listen for clicking.
  • Fuel injector clogging happens due to hydrocarbons, sediment, and ethanol in fuel, which draws moisture and rust into the system, as well as debris from old fuel and storage tanks.
  • Injection cleaning additives cannot unclog fuel injectors while in the engine, and can actually worsen the problem by loosening debris and pushing it into the injectors.
  • The only guaranteed way to unclog fuel injectors properly is through ultrasonic cleaning by a professional service, which removes injectors from the engine, cleans them with approved equipment, replaces worn parts, and tests for proper fuel flow.
  • Dead fuel injectors are those that lack resistance and do not respond to electrical input, and cannot be repaired, but must be replaced with a matching unit.
  • If a vehicle has sat with fuel for an extended period, the entire fuel system may need cleaning, rather than just the fuel injectors.
  • Proper diagnosis and cleaning of fuel injectors can save money and time, and prevent further damage to the vehicle’s engine.


In this article, we have covered the topic of dirty fuel injectors. We learned the two most common types of fuel injection systems. Then we learned the symptoms of dirty injectors

After that, we covered the diagnostics process and the cleaning process. Lastly, we discussed the costs involved in sorting this problem out permanently.


Now let’s answer some frequently asked questions.

What Is Injector

An injector is a component in the internal combustion engine. This injector is specifically designed with the sole purpose of injecting fuel into the engine. This injector is basically a valve that opens and closes with the help of a solenoid that is mounted inside of the injector.

How Many Fuel Injectors Does A Car Have

The number of injectors depends on the number of cylinders. On each cylinder, there is a single injector. Even though there are some vehicles that have both port and direct injection and they could have up to two injectors per cylinder.

What Causes Dirty Fuel Injectors

This problem is mostly caused by using dirty fuel. Or possibly you have a bad fuel filter that is not doing its job of cleaning the fuel. So, the dirty fuel inside of the gas tank is not cleaned properly and ruins your injectors in the process.

Can Dirty Fuel Injectors Cause Misfire

Yes, they definitely can cause the engine to misfire. Especially if the spray pattern is not good. There could be premature explosions inside of the cylinder that will make the engine misfire and cause a ton of issues.

How To Fix Dirty Fuel Injectors

Fixing dirty fuel injectors is possible by using carb cleaner if you know how to remove the fuel line and pump carb cleaner while the car is running. Or if you don’t know anything about mechanics. You look at your local parts store for injector cleaner. Just pour this solution into the gas tank and drive the car like this, it should clean the injectors.

How To Replace Fuel Injectors

Replacing injectors on port injection is fairly simple. Just remove the fuel line and they will pop out. Then plug the new ones back in and you will be good to go. While replacing injectors on direct injection cars can be a real pain and these are really hard to be removed.

How To Clean Fuel Injectors Without Removing Them

You can purchase one of the solutions that are sold online. Just go on Amazon and look for fuel injector cleaner and there are a ton of products. And they are dead easy to use. Just pour the solution into the tank and run the car like this, it should definitely clean them real nice.

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