If you’ve encountered any of the symptoms, the next logical question is what causes throttle body problems?

Well, this article will hopefully give you some answers and information or perhaps help solve the problem.



Before we start about what causes throttle body problems, we’ll just mention a few words about this vital car part.

The throttle body is located on the air intake manifold. It’s essentially a big valve that regulates the airflow into the manifold and engine.

By regulating the airflow, it regulates the acceleration. So when you press the gas pedal the metal plate inside (aka the butterfly valve) opens and lets more air inside causing the car to accelerate.

Modern throttle bodies are almost all electronic. This means it has a small electric motor on it that moves the butterfly valve when you press the gas pedal. The connection between the electric motor on the throttle body and the gas pedal is with wires. Sort of a fly-by-wire system.

Another option is a mechanical throttle body. The gas pedal, in this case, is connected to it with a metal cable. This is mostly found on older type cars and is perhaps more durable and simple to maintain.

The location of the throttle body (in most cases), is after the air filter housing and tubes, mounted on the air intake manifold.

If you’re interested in a more in-depth explanation provided by Wikipedia, click here.



1. Filth, grime, and gunk build-up


This is by far the most common reason what causes a bad throttle body. Especially if the car has some higher mileage on it.

Grime and filth deposits can be caused by various reasons like low-quality fuel, the engine burning oil poor maintenance, etc.

Once the grime builds up on the inner part of the throttle body, it starts jamming the butterfly valve, slowing it down when it opens and closes. In more severe cases, it can totally block it.

The common solution is to clean the throttle body, either by taking it off completely or when it’s on the car.

If you want to see how to do this, click here for a separate article on that topic or watch our YouTube video tutorial.


2. Presence of vacuum leaks


Vacuum leaks cause excess, unneeded air to be sucked into the system. This means more air getting into the system than the throttle body „allows“, causing problems with the air-fuel mixture.

The problem is usually caused by broken air tubes or hoses, leaking gaskets and seals, loose or broken clamps, etc. More rarely, problems can be caused by leaking actuators, valves, regulators, or solenoids.

Fixing the problem, in most cases isn’t that hard and consists of changing a tube, hose, or clamp or even just a simple clamp tightening.

The bigger problem is finding where the leak is in the system. This can be a hard and time-consuming task considering how many tubes, hoses, clamps there are.


3. Failure of the throttle body mechanism


In most modern cars, the butterfly valve on the throttle body is driven by an electric motor.

You’ll easily recognize it as a sort of plastic box on the side of the throttle body with an electric connection coming from it.

The motor is connected to the butterfly valve through a mechanism that has an assembly of cogs and levers.

Problems are caused mostly by material fatigue or physical damage (like the forced opening of the butterfly valve). This then leads to the mechanism breaking or getting stuck.

If this happens, the electric motor can, consequently, burn out.

The best remedy for this fault is to replace the complete throttle body. Most are made as one solid part and seldom is it possible to replace only the mechanism or electric motor.

Malfunctions like these can also happen to mechanical throttle bodies (where there is no electric motor) although less likely.

Due to more simple and rigid construction, these are somewhat less prone to failure. Also, on most cars, these can be dismantled, cleaned, and returned without much trouble.


4. Electric connection problems


To be honest, this fault is one of the rarest. Most manufactures make these connections secure and well made. Most of these faults happen on higher mileage cars where material fatigue starts taking its toll. These connections are, after all, constantly subdued to heat.

Another reason may be physical damage due to some previous repair or another kind of intervention.

These may then lead to filthy, loose, or corroded connections, broken wires, and other problems which prevent the electric motor and butterfly valve from working properly.

The solution is simple: cleaning and tightening the connections or in the worst case, replacing the connectors totally. In the case of broken wires, it may be more complicated as finding where it’s broken usually takes some time.


5. Bad throttle position sensor


As with all sensors, the throttle position sensor can also malfunction. When this happens, the butterfly valve may either stay shut or will not open properly.

You’ll recognize the sensor, in most cases, as a plastic part with an electric connection on it although there are other systems. It will be bolted to the throttle body.

The best and in most cases only remedy for this problem is a replacement.



Knowing what causes throttle body problems is one of the most important parts of car knowledge.

Have in mind that these problems, among else, mean trouble with driving and safety on the road.

Besides this, having some prior knowledge and information may give you some advantage and perhaps save some money.

Most important: if you do conclude that your car problem is caused by the throttle body don’t wait. Tend to the problem as soon as possible.



Written by: Sibin Spasojevic


Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com