Leaking Fuel Injector Symptoms and How to Fix It

Leaking fuel injector symptoms let you know that there is a problem with your fuel injectors and it’s best to fix it before it becomes too expensive to repair. From poor gas mileage to poor emission performance, there are symptoms you need to keep in mind.

Leaking Fuel Injector Symptoms

Fuel injector leakage is a bit expensive to repair, so after doing so, you should focus on preventing the same problem by cleaning your injectors regularly and using high-quality fuel. In this guide, we will look at the symptoms of a leaking fuel injector

A List Of The Top Leaking Fuel Injector Symptoms 

It’s important to service your vehicle regularly to prevent potential problems with your injector. Here are some of the symptoms of bad fuel injectors that you should keep an eye out for. 

1. Fuel Consumption Increases

Leaking Fuel Injector 

Main Sign  You’re using more fuel than usual
How to Test Fuel injector tester 
Possible Cause
  • Clogged injector 
  • Improper installation of your injector 
  • Worn seals 
  • A faulty pressure regulator 
How to Fix It 
  • Replace the seal 
  • Clean the injector 
  • Replace it completely. 


The main symptom of a leaking fuel injector is an increase in fuel consumption. You might notice that you are using more fuel than usual, and this will be because the injector has a broken seal. In worse cases, the injector might be clogged or have a faulty pressure regulator, causing the fuel to spill out of the injector before it can be used for your car.

If you notice that you have poor fuel economy, it is best to check if the seal is worn out. Then, you can replace the seal and check if it still needs replacement. In other cases, if your injector is clogged, you need to clean it to clear it out. It’s important to keep your injector clean through regular maintenance, as deposits can build up in them. 

You can purchase a kit to repair your bad fuel injector from an auto body store. The kit will offer you all you need to fix the problem, including a new injector and seal, but they are pretty expensive. If you’re unsure about fixing your injector by yourself, you should take your car to a mechanic and let them know that you are consuming more fuel than usual. 

2. Check Engine Light is On

Checking Engine Light

Main Sign  The warning light is illuminated on the dashboard
How to Test Use an OBD2 Scanner 
Possible Cause Damaged injector seals 

Improper injector installation 

How to Fix It  Replace the seal or the entire injector.


If your check engine light is on, that can be because of different reasons. It’s best to check the cause of the warning light first before you decide that the injector is damaged. You can do so with an OBD2 scanner. Connect the scanner to the OBD port of your car and put the key in the ignition without turning it on. 

Then, you can check the OBD code. If it is P02AD, that means that there is a problem with the fuel delivery system of your car. You can check the meaning of the code with the OBD scanner manual. If it is not the injector, you might have to visit your mechanic to repair the other problem. For a clogged injector, it might either be P0171 or P0174. 

After this, you will have to check the cause of the leaking injector, whether it is clogged because it has a build-up of deposits or the injector seal has been damaged or worn out over time. In worse cases, the entire injector is damaged, but there’s a good chance that the engine warning light will come on before then. 

You can also have your car inspected by a mechanic to check the cause.  

3. Rough Idling

Fuel Injector Tester 

Main Sign  The engine is not firing consistently 
How to Test Fuel injector tester 
Possible Cause Clogged injector 
How to Fix It  Clean the injector thoroughly. 


Rough idling in your car means that the engine is not firing consistently when your car is in the park. Most times, rough idling is caused by a bad spark plug, but it can also be because of leaking fuel injectors. The injector is meant to dispense fuel and air into the cylinders. The possible cause of rough idling due to an injector is a dirty or clogged injector.

Your fuel injection system can become clogged due to a build-up of deposits. This causes the injector to mix the fuel with air, creating a rough idle. If you notice your car is rough idling due to your fuel injector, you should purchase a cleaner for fuel injector cleaning. Follow the instructions on the cleaner and make use of a brush to scrub the injector clean.

Keep in mind that after cleaning your injector, you need to wipe away any fuel injector cleaner left on it. This ensures that it doesn’t mix with other parts of your engine. After cleaning the injector, you should seal it using a sealant that is compatible with the type of injector that you use. Apply the sealant based on the instructions of the manufacturer.

If your injector is sealed, it will no longer leak, and your car won’t idle roughly. 

4. Engine Misfires 

Dirty Fuel Injector

Main Sign  Misfires upon engine startup or during engine idling
How to Test OBD2 scanner 

Fuel injector tester

Possible Cause
  • Clogged or dirty injector 
  • Faulty injector
How to Fix It 
  • Clean the injector 
  • Use a repair kit 
  • Replace it outrightly. 


A clogged or dirty fuel injector can also cause your engine to misfire. If you have a leaking fuel injector, you might notice that your engine is sputtering, and this is sending vibrations through the car. With a clogged injector due to deposits building up, your fuel can start leaking into the engine and cause even more damage.

In worse cases, parts of the seals of the injector will be worn out or damaged, and this will lead to leaks. If there are leaks in your engine, it will start misfiring. Further, a clogged fuel injector causes air and fuel to mix together, causing misfires when you’re idling or when you just start up your car. If your engine misfires, the best thing is to see a mechanic immediately.

If you can fix your fuel injection systems by yourself, you should do so with cleaning. You can purchase a brush, high-quality cleaner, and a sealant to properly clean your injector. It is important to wipe off the cleaner and let the sealant dry before reconnecting the fuel injector. If you clean it and it still misfires, you should purchase a repair kit or contact a mechanic. 

5. Gasoline Odor in the Car 

Gasoline Odor in the Car

Main Sign  You can smell fuel coming from your car
How to Test Fuel injector tester
Possible Cause Leaking fuel injector
How to Fix It  Replace the injector, or contact a mechanic. 


Another leaking fuel injector symptom is the smell of gas in your car. If you notice a gasoline odor in your car, the first thing you should do is check where it is coming from. If it is coming from the engine compartment, then that means your fuel injection system is leaking and will need replacement.

Also, if you smell the fuel odor from the exhaust, this means too little air or too much fuel is leaking into the vehicle’s combustion chamber. Most times, this is because of fuel leaks due to the injector. If this isn’t the case, you should check the air filter or mass airflow sensor. If you’re driving and you start smelling gas, it’s best to pull over first and check the source of the smell.

It is best to contact a mechanic if you are unsure what to do. If you’re handy with cars, the best next thing to do is purchase a repair kit that comes with seals and an injector. You can replace the entire injector and the seals and give your car a test run while looking out for the smell. If it still happens, then you will have to check other parts of the fuel system.

6. Poor Emission Performance 

Poor Emission Performance

Main Sign  Black smoke from the exhaust pipe
How to Test Fuel injector tester
Possible Cause
  • Leaking injector 
  • Faulty fuel pressure regulator
How to Fix It  Replace the injector 


If you notice black smoke coming from the exhaust pipe, this is due to poor emission performance. This could be because of a leaking injector or if the fuel pressure regulator in the injector is damaged. In some cases, it could also be a damaged air filter. Black smoke means that the fuel injectors are adding too much fuel due to the leaky fuel.

With black smoke from the exhaust pipe, your engine is running rich on too much fuel, and this can cause severe damage to your engine. An engine is running rich when it has too little air or too much fuel, mostly due to the injector. The best thing to do is check the source of the leakage, whether it is clogged or the seals are worn out or damaged.

You can start by cleaning the injector thoroughly and then installing new seals. This is the most inexpensive option. If the color of your exhaust smoke does not change after this, you should consider replacing or repairing the fuel pressure regulator, as this is another major cause. 

If this symptom happens just after installing an injector, there’s a chance that this was done incorrectly. You should remove the injector, clean it, seal it, and then install it again. If the symptoms continue, you need to visit a mechanic. 

Are Leaking Fuel Injectors a Possible Cause of Water in the Gas Symptoms?

Leaking fuel injectors can indeed contribute to water in the gas engine symptoms. When fuel injectors malfunction and begin to leak, water can seep into the fuel system. This causes a variety of problems, including rough idling, misfires, decreased engine performance, and potentially engine damage. Identifying and addressing leaking fuel injectors promptly is crucial to prevent further complications associated with water in gas engine symptoms.


It’s important to check for the leaking fuel injector symptoms if you suspect that there is something wrong with your injector. Here is a rundown of the symptoms you should check:

  • An increase in your fuel consumption or reduced gas mileage can be caused by a clogged injector, worn-out seals, faulty pressure regulator, or bad installation.
  • If the engine warning light is on, use an OBD 2 scanner to check the cause, and if the code starts with P02, you will need to inspect your fuel injectors.
  • Rough idling when your car is in park can be because your fuel injector is clogged and leaking, leading to a poor mixture of air and fuel going into your engine.
  • Engine misfiring upon startup or while idling can be because of a clogged injector or a faulty injector, and you will need a repair kit or a mechanic.

The injector is a highly important part of your engine, so you should maintain it regularly to prevent leaks or further damage to your engine. If you notice any of these symptoms, check for the cause or visit a mechanic. 


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