Oil In Throttle Body – [Cauese, Symptoms & Fix!]

The throttle body of your car is a component of your car that helps to maintain the amount of air flowing into the engine. 

Air gets into the engine for the complete combustion of the fuel as oxygen is an important molecule for this chemical reaction to occur. 

But if there is oil in the throttle body, this may pose a problem and even lead to incomplete combustion. Find out more about the causes, symptoms, and solutions when there is oil in your car’s throttle body in this article.

4 Common Causes of Oil in Throttle Body

Here are a few reasons why you may find oil in your vehicle’s throttle body:


When your engine has gone many miles, it starts to age as the rings and seals become weak. More air will be able to get in because of the weakened components and that might lead to oil leaking out.

Too Much Pressure in Crankcase

The valves and piston rings are responsible for shading away the combustion gas. There are times when these components become faulty or break down, and during that situation, too much gas gets into the crankcase. 

Pressure starts to build in it and eventually, because of the force, oil is pushed to the breather which then gets passed on to the throttle body.

Use of Wrong Piston Rings

We have already mentioned the importance of piston rings in the combustion reaction above. 

Now, you will find two kinds of piston rings; one is made of cast iron and the other is moly rings. The right kind of ring has to be picked in accordance with the vehicle’s engine capacity.

If the wrong type of piston ring is used that is inadequate to hold blow-by gases, then a lot of pressure will be exerted on the crankcase. Eventually, oil will be forced out to the throttle body.

Failed PCV System

This sophisticated system is responsible for keeping blow-by gases away from your engine and it is done with the help of various piping. 

But when these piping get blocked somehow, the entire system falls under immense pressure. Thus, oil gets pushed into the inlet chamber.

So, this chamber is joined to the throttle body and the manifold, and hence, you will notice oil in those places because of this.

Read also: What To Do After Replacing Throttle Body?

Symptoms of Oil in Throttle Body

You can tell by looking at several things to know whether you have oil in your car’s throttle body or not. Here they are:

An Increase in Fuel Consumption 

When there is a crisis for air the engine has to work extra hard to run properly which leads to more oil consumption. 

But you should know, there may be various other reasons why the fuel economy of your car is bad.

Read also: Electronic Throttle Control Red Lightning Bolt

Slow Acceleration

Throttle bodies are designed in a way that they can detect the amount of airflow that goes inside the engine. 

These are done by special sensors, which after detection transfer data to the car’s computer. With the help of this data, the fuel injectors are monitored in each cylinder.

The fuel getting inside the engine is matched with the amount of air going into the engine because of this regulation. We could say that the throttle body’s function is to also maintain the ratio of air and fuel entering the engine. 

But when oil is present in the throttle, the functionality gets hampered, and the balance of the fuel and air brakes. 

Therefore, it leads to incomplete combustion and makes it hard for the car to accelerate properly and evenly.

Smoke Coming Out of Exhaust

When there is excessive oil in your throttle body, it can seep into the combustion chamber and get burned with a mixture of air and fuel. Hence, you might see an increased amount of white smoke coming out of your exhaust.

Check Engine Light Switches On

Nowadays, mostly all cars come with an electronic throttle control system that basically keeps track of how the throttle body is performing. 

So, when the ETC gets a hint of a problem with the throttle body the check engine light gets illuminated.

But there is a catch here, other problems unrelated to the throttle body issue can switch on the check engine light as well. Regardless of that, you should take your car to a professional whenever you see this light.

Related: Electronic Throttle Control Repair Cost

Rough Idling

The throttle body can’t function efficiently when there is oil, dirt, or other contaminants present on it. 

That results in a decreased level of air entering the engine. Since oxygen is not going in properly incomplete combustion will take place which will cause rough idling of the engine.


Incomplete combustion causes the car’s engine to misfire. But only oil in the throttle body does not result in this. 

If your spark plugs or other components are dirty your engine might misfire then too.

How To Fix Oil in Throttle Body?

Now that we are done talking about the cause and the symptoms of the problem, let’s get talk about what measures we can take to fix it. Here are a few ways that the issue will go away:

  • Replace parts of the engine or the entire engine when you have gone beyond the recommended miles.
  • Change the broken PCV vault.
  • Replace worn rings and valves. Understand what type of ring your engine can accommodate.
  • Fasten your rings properly as at times they are not properly sealed. Use professional help while doing this.
  • No sludge should be present in the piping of the PCV system.
  • Clean your car’s throttle body with the help of a throttle body cleaner.


1. Can one clean the throttle body by themselves?

Yes, you can if you have the proper knowledge and the right tools.

2. Can one replace the throttle body by themselves?

Yes, it is possible. But it’s better to get professional help when it comes to the replacement part.

3. Is it abnormal to have oil in the throttle body of your car?

Yes, it is. A little amount of oil does not cause an issue, but if it is excessive that can break down various parts of the car.

4. Is it better to replace or clean the throttle body?

You can replace the sensor and clean the throttle body. In most cases, you will not be required to replace the entire throttle body.

5. What is the lifespan of throttle bodies?

There are no proper indications for this particular thing. But it is always recommended to give a deep cleaning after every 75,000 miles.

Final Words

Do not ignore it when there is oil in the throttle body of your car as several parts of your car may get damaged and cause problems in performance as well. 

This includes increased consumption of fuel, slow acceleration, rough idling, etc. All you have to do is clean and replace parts when needed.

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