What Happens When Throttle Position Sensor Goes Bad?

What Happens When Throttle Position Sensor Goes Bad? Many components work together to give your engine a smooth acceleration and improve the overall performance of your vehicle. The throttle position sensor (TPS) is one of such components. The TPS monitors and controls the quantity of air that goes into the engine.

The throttle position sensor is a component of your car’s fuel management system that ensures the mixture of air and fuel sent to the engine is accurate. The throttle positioning sensor sends data to the vehicle’s control module (ECU) to release the amount of fuel that will be proportionate to the amount of air in the engine and a faulty one can affect the way your car accelerates and performs other functions.

In this article, we look at what happens when throttle position sensor goes bad. But before then, let’s find out what is a throttle position sensor.

What is a Throttle Position Sensor?

The throttle position sensor is a component that controls the quantity of air/fuel that is sent to the engine. The sensor controls the opening and closing of the throttle valve that sends air to the engine.

The TPS determines the position of the valve and relays the information to the computer to ensure the engine has the correct mixture of air and fuel for the proper acceleration and idling of your vehicle. It directly observes the position of the throttle valve and gives signals to send more fuel to the engine when the accelerator is pressed down.

There are three major types of TPS. These include closed throttle position sensors potentiometer sensor, and a combination of closed and potentiometer sensors.

How does the Throttle Position Sensor Work?

The ratio of air and fuel present in the engine determines how efficient it functions. The flow of fuel and air is controlled by the throttle mechanism which comprises components like the throttle valve and throttle position sensor.

The TPS monitors the position of the throttle valve and how much the gas pedal needs to be pressed for the car to accelerate. It then sends this information to the control module to take necessary action.

Since the throttle position sensor monitors the position of the throttle valve, when the valve is open, the engine receives a large amount of air which is supposed to be complemented with a significant amount of fuel. The TPS senses this and sends a signal to the engine control unit which then decides the adequate amount of fuel to be injected into the engine.

When a driver steps on the gas pedal to accelerate the car, the engine will require more fuel and air. It is the job of the throttle valve to open up and send air to the engine while the throttle position sensor detects this position and sends data to the ECU. The ECU then ensures that a proportional amount of fuel is also injected into the engine for combustion.

In older car models, the throttle position sensor was attached directly to the throttle body to detect its position through the contact they made. However, modern vehicles have employed more advanced technologies that allow the TPS to detect the valve’s position without any contact. The modern TPS uses magnetic fields that move as the throttle valve changes its position (opening and closing). The sensor monitors this movement and sends the data to the ECU for proper reading and necessary action.

Functions of the Throttle Position Sensor

The throttle position sensor plays a huge role in any vehicle. It ensures that the proper ratio of air and fuel is injected into the internal combustion engine.

The TPS sends data to the ECU when the throttle valve opens or closes which will then decide how much gas the fuel injection system should send to the engine for its operation.

The information received from the throttle position sensor is used with other information like; the air mass flow, air temperature, and engine revolutions per minute (RPM) to inject the exact quantity of fuel the engine needs at a certain time.

When the TPS is functioning properly, your acceleration will be smooth. The harder you press the gas pedal, the more the throttle valve opens, and more air enters the engine. The sensor immediately notifies the ECU which ensures more fuel is sent to the engine to balance the air-fuel ratio. In the next subheading, we discuss what happens when throttle position sensor goes bad.

What Happens When Throttle Position Sensor Goes Bad?

A faulty throttle position sensor can cause serious damage to your car. This damage can be evident in different parts of the vehicle.

Some indicators of a faulty throttle position sensor include:

Weak acceleration or inability to accelerate

A bad TPS will make it difficult to accelerate or cause the vehicle to jerk when you try to accelerate.

If the TPS is faulty, the control module will not be able to manage the flow of fuel and air into the engine because it is not receiving the correct signal. And if the engine is not receiving an adequate proportion of air and fuel, it will cause weak, delayed, or no acceleration.

Check engine light illuminates

The throttle position sensor is a vital component in a vehicle’s combustion process. If this component is bad, combustion will be affected which will in turn influence the general performance of the engine.

When the Engine Control Module senses a problem with the engine, it will make the check engine light illuminate. The dashboard will display diagnostic error codes such as P0121, P0122, P0123, P0124, P2135, and P2138.

Bad fuel economy

A bad throttle position sensor will lead to excess fuel consumption by the engine. This happens because the TPS is sending wrong signals to the ECM and the control module will then direct the fuel injectors to send in more fuel than required at a particular time.

Also, since a bad TPS can cause acceleration problems, your car will drive at a limited speed and will make your car spend more time on the road, thereby consuming more fuel.

Engine rough Idling

A faulty throttle position sensor will lead to engine rough idling.

Rough idling occurs when the engine’s RPM is below or above the range of 600 to 900 RPM per second when your car is parked or stopped.

If the TPS is the reason for a rough idle, it will cause the throttle valve to be unsteady. The valve will open and close intermittently, causing an unsteady airflow and RPM.

Engine stalling

A faulty throttle position sensor can cause the throttle valve to close when it is supposed to be open to send air into the engine. If this happens, the engine will stall while driving.

Also, a faulty TPS might send wrong signals to the engine control module and prompt it to send inadequate fuel to the engine. Lack of sufficient fuel in the engine will lead to stalling.

Poor engine performance

A faulty TPS will have a bad influence on the engine. You might need to press the accelerator or gas pedal harder than usual before you get the desired response from the engine.

How to replace a faulty Throttle Position Sensor at Home

To replace a faulty throttle position sensor at home, you will need the following: work gloves, safety glasses, a Voltmeter, and a screwdriver set.

Here are the basic steps to follow when replacing a faulty TPS.

  1. Arrange your tools so that everything will be organized and handy while you are working.
  2. Disconnect the battery. You must disconnect the battery’s negative terminal to prevent electric shocks or damage to other engine components.
  3. Locate and unplug the old throttle position sensor from the connectors or clips that connect it to the ECU.
  4. Remove all screws and keep them safe in case you may need them while installing the new throttle position sensor.
  5. Remove the old sensor, mount the new one, and screw it into the same position.
  6. Reconnect the connectors, wiring, and clips and ensure they are properly installed.
  7. Connect the negative battery terminal that was disconnected earlier, and the work is done!

Cost of Throttle Position Sensor Replacement

A faulty throttle position sensor needs to be replaced ASAP to avoid complications and damage to other components of the vehicle.

The TPS is not an expensive component to replace. It costs between $110 to $150. The TPS will cost about $75 to $105 while labor is between $35 to $95 if you are getting it fixed at an auto repair shop.

Frequently Asked Questions

Where is the Throttle Position Sensor located?

The throttle position sensor is found inside the throttle body and the throttle body is in the engine, in between the intake manifold and air cleaner. The TPS is located inside the shaft of the butterfly valve in the throttle body.

How long will my Throttle Position Sensor last?

The throttle position sensor is designed to last as long as the lifespan of your vehicle. However, driving habits and conditions or a problem with another engine component can lead to its early damage. You must replace the TPS once it is faulty.

Can I drive with a bad Throttle Position Sensor?

You can drive with a bad throttle position sensor. However, doing this will make driving difficult and can put you, pedestrians, and other drivers in a dangerous situation. A bad TPS will make it difficult to accelerate or idle properly which will make driving rigid.

Will a faulty Throttle Position Sensor cause the Engine to shut down?

Yes! A faulty throttle position sensor is capable of shutting down the engine. This can happen because a faulty TPS will affect the opening and closing of the throttle valve which will restrict the required quantity of air from getting into the engine. Also, a faulty TPS will send wrong signals to the Engine Control Module which might fail to direct the right amount of fuel to the engine for combustion.