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How to Tell If You Have a Bad Throttle Position Sensor

CarPart  ·  October 27, 2022

How to Tell If You Have a Bad Throttle Position Sensor

Cars and other vehicles have relied on sensors for the longest time. Still, newer models have many more sensors than ever before, all to keep up with the high-tech features that now come standard. One of the most crucial of those is the throttle position sensor.

The throttle position sensor is attached to the throttle body. It measures how far the throttle valve opens so the engine can match that air intake by injecting the correct amount of fuel. Signs of a throttle position sensor going bad include an illuminated check engine light, delayed acceleration, jerking even when idle, engine stalling, and fuel economy issues.

This guide will help you understand a throttle position sensor and how it works. You’ll know how to tell if you have a bad throttle position sensor by looking out for its symptoms.

Recap: What Is a Throttle Body, And What Does It Do?

The throttle position sensor is only one of countless sensors in your vehicle, an incredibly critical component that can affect your engine’s performance.

To understand the throttle position sensor, we must take a step back and talk about the throttle body to which that sensor is attached. Once you know what the throttle body does, you’ll have no problems understanding the throttle position sensor.

As you might already know, internal combustion engines must mix fuel and air in the correct amounts to generate power. When that happens, fuel combusts, and your engine drives your car forwards.

What the throttle body does is control the engine's air intake. It is a valve that opens and closes depending on how hard you press the accelerator pedal.

The harder your foot pushes that pedal down, the more the valve opens to let air into the engine. Conversely, as you let go of the pedal, the throttle body closes and stops or reduces the amount of air getting in.

What Does a Throttle Position Sensor Do?

Remember two things: first, internal combustion can only happen by combining air and fuel; second, your foot on the pedal controls how much air enters the engine. The throttle position sensor relates to the ‘fuel’ side of that equation.

Simply put, the throttle position sensor measures how far you've opened the throttle valve (by pressing down on the accelerator). 

Based on this data, the ECU determines the timing and amount of fuel to inject into the engine.

So, when the throttle position sensor works correctly and does what it’s supposed to, your engine will combust the perfect balance of fuel and air to give your car the power it needs to perform.

What Are the Symptoms of a Bad Throttle Position Sensor?

At this point, it should be clear just how critical the throttle position sensor is to your engine’s overall functioning. It’s so important that if it fails, the symptoms of a bad throttle position sensor become more pronounced and almost impossible to ignore.

Here are 5 ways you can tell if you have a bad throttle position sensor:

#1. The Check Engine Light Turns On

Like most engine problems, a bad throttle position sensor will trigger the check engine light to illuminate your car's instrument panel. 

However, problematic throttle position sensors cause the Check Engine light to flash intermittently. 

#2. Delayed Acceleration

Another tell-tale sign of a bad throttle position sensor is delayed acceleration.

Remember: the throttle position sensor determines how much fuel to inject based on how much air is coming into the engine.

So, when that sensor is faulty, the car will take a few moments to accelerate even after you press harder on the accelerator.

#3. Surges, Bucking and Jerking

Unfortunately, delayed acceleration isn’t the only problem you’ll experience when you have a bad throttle position sensor. Unwanted surges, bucking, and jerking are also symptoms of faulty throttle position sensors that make driving unsafe.

Just as a bad sensor causes fuel injection delays, it can mistakenly trigger more fuel to enter the engine when it’s not needed. As a result, the combustion process in your engine goes haywire, making your car jerk around even while idling.

#4. Engine Stalling

Of course, anything that disrupts an engine's air or fuel intake can cause it to stall entirely. That's undoubtedly true with bad throttle position sensors when they cause no fuel to enter the engine.

#5. Long-Term Fuel Economy Issues

Symptoms #1 to #4 are pretty obvious because they happen in the short term. Sadly, you might not even know you have a bad throttle position sensor until much later.

That’s because the sensor can lead to fuel economy issues. 

For example, your car might burn too much fuel and cause an increase in your fuel spending, but you’ll only notice the increase over an extended period.

What Causes a Throttle Position Sensor Failure?

A typical throttle position sensor has a lifespan of about five years, after which it can start having issues.

However, excess wear from old age isn’t the only thing that can cause symptoms of a bad throttle position sensor.

Electrical faults and issues with the throttle position sensor wiring harness can also cause it to fail, leading to all the symptoms you saw listed above.

Here are a few examples of what could cause your throttle position sensor to fail:

Whether you need a new throttle position sensor or a mechanic to troubleshoot the one you have, finding the best nearby automotive businesses is easy. 

Just check out the Directory at CarpartAU to narrow down the ones in your area and get in touch with them immediately!


By Ray Hasbollah


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