Symptoms of a Bad Throttle Body | How to Replace a Throttle Body?

The throttle body is one of the major mechanical parts of your vehicle. It is most commonly found in fuel-injected vehicles. It uses to regulate and control the air entering the engine. In this article, we will deeply discuss the function, location, replacement cost, and symptoms of a bad throttle body.

What is a Throttle Body?

A throttle body is a tubular designed housing that contains a valve that moves to change the amount of air entering the engine. In simple words, the throttle body controls the amount of air entering the engine cylinder.

Throttle Body

A good working throttle body delivers a precise amount of air and fuel to the engine, which helps to improve the engine’s performance. However, if the throttle body is damaged by an inappropriate air-fuel mixture, the combustion process will not function properly, which may lead to engine misfiring.

When the throttle body goes bad, it generates different symptoms, such as check engine light illumination, misfiring, engine stalling, poor acceleration, poor fuel economy, or poor engine performance.

Symptoms of a Bad Throttle Body

A faulty or bad throttle body generates one or more of the below-given symptoms:

  • Illuminated Check Engine Light
  • Stalling Idle
  • Rough
  • Acceleration
  • Electrical
  • High RPM Idle
  • Rough Idling
  • Poor Engine Performance
  • Poor Fuel Economy
  • Misfires

1) Illuminated Check Engine Light

The illuminated check engine light is one of the first symptoms of a bad throttle body. Your check engine light may also come on for other reasons as well. Because of this, it’s a good idea to go to an auto professional and have your vehicle scanned for trouble codes when you put it on the dashboard.

check engine light

2) Stalling Idle

Engine Stalling

The bad throttle body affects RPM in other ways as well. It may reduce the idle speed due to that your engine may stall. This usually happens when there is a lot of soot and contamination on the throttle body’s tail. As a result, less air gets into the engine, and the idle speed drops.

3) Rough Acceleration

The throttle body controls the air/fuel mixture entering the combustion chamber. Therefore, when the throttle body goes bad, it doesn’t properly supply air and fuel to the combustion chamber. When the combustion chamber doesn’t receive the required amount of air-fuel mixture, it doesn’t generate power according to requirements, leading to poor acceleration.

acceleration problems

4) Electrical Issues

A faulty electrical connection may transmit wrong data to the vehicle’s powertrain control module (PCM).

When the throttle body doesn’t send correct data to the PCM, your PCM doesn’t regulate the air-fuel mixture according to the requirements, which may generate different issues. In such conditions, your vehicle may trigger into limp mode due to that your car’s engine loses a lot of power.

5) High RPM Idle

Unstable Idle Speed, signs of bad throttle body

The throttle body regulates the idle speed of the engine so that the speed remains constant at all times. High RPM idle may occur if there is a problem with the throttle body.

However, a misaligned throttle valve may also lead to this issue. You can rectify the main issue by using a diagnostic scanner.

6) Rough Idling

Rough idling is another symptom of a damaged or faulty throttle body. If you observe your vehicle’s engine idling and making strange noises, it means there is something wrong with your throttle body or throttle valve.  

Rough Idle due to bad throttle body

Your vehicle’s engine becomes sensitive at idle, which may help you to identify a bad throttle body. However, there are many other issues that may lead to rough idling.

Read More: Why Car Shakes at Idle?

7) Poor Engine Performance

An engine needs a sufficient supply of air and fuel to run efficiently. If your engine is not getting sufficient airflow due to a damaged throttle body, the engine will suffer, resulting in poor engine performance.

poor engine performance

If the vehicle feels like it loses half of its power when accelerating, it’s definitely due to a faulty throttle body.

Read More: Why Vehicle Loss Power While Driving?

8) Poor Fuel Economy

Poor fuel economy

Poor fuel economy is one of the common symptoms of a faulty throttle body. The poor fuel economy indicates that your throttle body needs cleaning. A vehicle’s mileage is best measured from full tank to full tank.

You must fill up your gas tank and register your odometer or reset one of your trip meters to zero before you can use your vehicle. If the tank is empty, refill it and repeat all the steps again.

Divide the distance traveled by the amount of fuel used. This will provide the mileage of your car. If the difference between two full tanks of fuel is more than 15 percent, your vehicle may have a throttle problem.

9) Misfires

An engine misfire is one of the clear symptoms of a bad throttle body. As we discussed above, the throttle body ensures the proper supply of air-fuel mixture to the engine cylinder. However, when it goes bad, it doesn’t supply sufficient air-fuel mixture to the engine cylinder, which leads to misfiring.

engine Misfiring due to faulty throttle body

Misfire occurs when the air/fuel mixture is poor, or the spark plugs have a weak spark.

Read More: How to Clean Throttle Body?

What are the Causes of a Bad Throttle Body?

One of the main causes of a bad throttle body is the accumulation of contamination inside the body. Dirt buildup will prevent the throttle body from operating properly and will cause problems with airflow control.

The vacuum leak is another reason for a faulty throttle body. As a result, “false air” is inhaled, so the total amount of air inhaled does not correspond to the throttle valve position.

A wrong-adjusted throttle position sensor can also cause an engine to run badly. 

 Throttle Body Replacement Cost

The replacement cost of the throttle body varies according to the vehicle model, labor cost, and type of brand. The average throttle body replacement cost is from $240 to $660. In this cost, the throttle body cost is from $210 to $490, while the labor cost is from $30 to $170.

FAQ Section

Where is Throttle Body Located?

The throttle body is usually located in the intake manifold on the large hose from the air filter or turbocharger. Aluminum is typically utilized to make throttle bodies. The position of the throttle body may differ slightly according to the vehicle model. However, depending on the intended use of the throttle body, it should be located somewhere between the intake manifold and the air filter.

Can I replace the throttle body myself?

Yes, you can replace it yourself. The replacement of the throttle body on most vehicles is usually fairly easy. However, some vehicles require a diagnostic scanner to reset/calibrate the throttle body after replacement, and most people do not have such a scanner at home.

Does cleaning the throttle body make a difference?

Yes, cleaning the throttle body can make a difference, but it depends on how dirty it is. Over time, the throttle body can become fouled with carbon deposits, oil residue, and other sticky substances that can build up. A clean throttle body works more efficiently, which helps to improve fuel economy and engine efficiency. Therefore, when your throttle body is clogged, you should clean it as soon as possible.

Can I drive with a bad throttle body?

Yes, you can drive, but it is not recommended. A bad throttle body leads to various drivability issues, such as poor engine performance, engine stalling, poor fuel economy, and misfiring. Most of the time, the car won’t start when the throttle fails.

How do you reset a throttle body?

According to the make and model of the car, there are several methods to reset the throttle body. Few models require batteries to be disconnected for a while to allow the system to reset. If not, you’ll need diagnostic tools to reset your settings. Consult the service manual for your specific vehicle model.

What happens if you drive with a bad throttle body?

If the throttle body is bad enough, the vehicle can be stopped. Driving with a bad throttle body generates different symptoms such as rough idle, check engine light illumination, engine stalling, poor acceleration, poor fuel economy, misfires, and high RPM idle.

Will a throttle body throw a code?

Yes, a faulty throttle body can trigger a trouble code. A damaged throttle body is one of the most common reasons for the check engine light illumination. If you see a small amber light on the vehicle dashboard, you should immediately inspect your throttle body. The trouble codes related to the throttle body are P2101, P2110, P2112, P2118, and P2135.

Is there a fuse for the throttle position sensor?

One of the easy methods to reset the throttle position sensor is to disconnect the negative battery cable for up to 5 minutes or remove the fuse for the PCM.

How do I know if I need a new throttle body?

If you observe one of the below-given signs, it indicates that you need a new throttle body:

  • Illuminated Check Engine Light
  • Misfires
  • Poor Fuel Economy
  • Stalling Idle
  • Poor Engine Performance
  • Rough
  • Acceleration
  • Rough Idling
  • Electrical
  • High RPM Idle
Read More

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