Do Diesel Engines Have Throttle Body? [We’ve Got The Answer]

Whether you drive a diesel or a gasoline engine, you’ve probably heard “throttle body.”

A mechanical throttle body is a piece of engine equipment that controls the amount of air needed to inject fuel into your engine.

Throttle bodies are required for gasoline engines.  Since diesel engines are designed to run lean, they don’t need throttle plates to run.

Throttle or No Throttle On Diesel Engines

All modern diesel engines no longer require a throttle body because, unlike gasoline engines, diesel engines are throttled directly by fuel rather than air.

However, throttle bodies are required on carbureted diesel engines (older diesel models) because a throttle body is built into the carburetor.

Though they are no longer required, you can still install throttle controls in your diesel engine if you want to improve its performance.

Using throttle bodies on your diesel can improve engine performance in ways such as:

  • Controlling exhaust gas recirculation is made easier
  • Minimize the engine from shuddering and making loud noises when the engine is turned off

Diesel vs. Gasoline Engine Throttle Body

YouTube video


Since modern diesel engines have always used direct fuel injection, they do not require a throttle body. So when you step on the accelerator, the fuel injector will supply more diesel to generate more power without air assistance.


Because gasoline engines are air-injected, they require a throttle body to provide power to the engine. The throttle body will function as a valve to regulate the amount of air that can enter the engine. Generally, the more air enters the engine, the more fuel is injected, and the more power produced.

Read More:  Can A Dealer Sell A Car With Frame Damage? [Things to Know]

Faulty Throttle Body Symptoms

A good throttle body can improve engine performance; however, a bad one will degrade it by interfering with the engine’s air/fuel mixture, resulting in poor running conditions. The following symptoms may indicate that your throttle body needs to be replaced.

Jumpy Idling

Because the car engine is most sensitive at idle, it is easier to detect your vehicle’s health. When you idle your car and notice unusual jumping and strange noises, you may have a faulty throttle body. 

Stalling When Idling

In contrast to jumpy idling, when your engine stalls, it is a sign that your throttle system is malfunctioning. It states that your throttle valve is always open, constantly allowing exhaust gasses to enter your throttle system.

Erratic Acceleration

Stepping on the accelerator can also help you manage the health of your EGR system. If you notice erratic acceleration in your vehicle, it could be due to a faulty throttle body.

Unusual Fuel Consumption 

A faulty throttle body may cause you to need to refuel more frequently or less frequently.

Low Driving Performance

When you notice that your car isn’t accelerating enough as it should, it could be due to a faulty throttle body. Your valve may be constantly opened or closed.


Something is wrong with your throttle controls when you hear knocking noises from the engine. It claims that your throttle valve is permanently closed.


A faulty throttle body can disrupt the air-fuel mixture and cause your engine to misfire. Misfires occur when the air-fuel ratio is incorrect and combustion inside the combustion chamber is incomplete due to faulty throttle controls.

Read More:  How Much Ethanol is in 87 Octane Gasoline: Understanding Ethanol Content Levels

Frequently Asked Questions

Why is a throttle body not required on a diesel engine?

It’s because diesel engines don’t actively use air intake control mechanisms. Diesel engines, unlike gasoline engines, are throttled by fuel rather than air.

Does a Duramax diesel have a throttle body?

No, Duramax Diesel Engines do not have throttle bodies. They instead have an EGR system with a butterfly valve.

Do diesel engines have a throttle position sensor?

A TPS sensor is used to monitor an engine’s air intake. The sensor is typically mounted on the butterfly shaft to monitor the throttle position directly.

Since diesel engines lack a throttle body, they will also lack a throttle position sensor.

What causes my throttle body to fail?

One of the common causes of a faulty throttle body is internal contamination. The throttle valve can no longer move properly due to contamination such as filth, carbon, and dirt that has accumulated in the throttle body, causing issues with air supply control.

Leave a Comment