By definition, a throttle position sensor (TPS) is a sensor used in internal combustion engines that measures the position of the throttle valve, which regulates the flow of air and fuel into the engine.

Where is TPS mounted?

The TPS is typically mounted directly on the throttle body and consists of an electrical sensor that sends voltage signals to the engine control unit (ECU) about the position of the throttle valve.

The Engine Control Unit (ECU) then uses the signals provided by TPS to adjust engine load and fuel combustion in accordance with the accelerator given by the driver.

TPS also plays an important role in the additional functionalities of most modern cars:

• The function of TPS in Cruise Control:

The throttle position sensor (TPS) helps the engine control unit (ECU) regulate the engine’s speed and power output as desired.

• The function of TPS in Electronic Stability Control (ESC):

Most of the cars made after 2008 use ESC as a pro-safety feature. The TPS is used to detect sudden changes in the accelerator pedal position, which can indicate a loss of control. And help the system apply brakes to individual wheels to prevent skidding or sliding.

1. Purpose of TPS:

Initially, TPS plays a crucial role in ensuring the efficient and optimal operation of the combustion process taking place inside the engine.

The signal sent by the TPS is monitored by the ECM (Engine Control Module. The brain of your car) as part of the continuous monitoring of the vehicle’s systems and performance.

If the ECM detects a fault reported with the TPS or throttle body. It will typically set a Diagnostic Trouble Code (DTC) (to learn more about a DTC code, jump straight to V. TPS Diagnostic Trouble Codes) and illuminate the “Check Engine” light on the vehicle’s dashboard.

2. TPS Components:

The components that make up a typical TPS (throttle position sensor) for a car engine may include the following:

1. Housing: A plastic casing that encloses the TPS components and attaches them to the throttle body.
2. Sensor element: A variable resistor/potentiometer that detects the position of the throttle plate and changes. Its resistance to alternate the flow of voltage to signal the ECM accordingly.
3. Electrical connectors or wires: The connectors or the wires allow the TPS to communicate with the engine control module. Most of the cars have a 3/4-pin TPS connector.
4. Retaining screws: Screws that secure the TPS to the throttle body.
5. TPS Operation:

In a TPS (Throttle Position Sensor), the mechanism works in the following way:

This signal is used by the ECM to adjust the fuel injection and ignition timing for optimal engine performance and fuel efficiency.

When the car is started, the ECM sends a 5-volt reference voltage to the TPS via the 5-volt reference wire. The TPS then sends a voltage signal back to the ECM via the signal wire, which varies depending on the position of the throttle plate. The ECM uses this signal to adjust the fuel injection and ignition timing to maintain optimal engine performance.

As the throttle plate is opened or closed, the variable resistor in the TPS changes its resistance, which alters the voltage on the signal wire. The ECM continuously monitors this voltage signal and adjusts the engine operation accordingly.

4. TPS Diagnostic Trouble Codes:

A DTC is a code that is generated by a vehicle’s onboard diagnostic system (OBD-II) when it detects a problem. Or fault with one of the vehicle’s systems or components.

Fun Fact: Almost all cars around the world made after 1996 have an OBD-II system in them. Does your car fall in this category?

The specific DTC code for a faulty throttle position sensor (TPS) can vary depending on the make and model of the vehicle. However, in general, TPS-related DTC codes typically start with the letter “P,” which stands for the powertrain.

Here are some examples of TPS-related DTC codes:

• P0120
• P0121
• P0122
• P0123
• P0220
• P0221
• P0222
• P0223

It is important to note that these codes can also be triggered by other problems with the engine or transmission, so further diagnosis may be necessary to confirm the root cause of the issue.

5. TPS Code Interpretation

There are specific diagnostic tools and scanners (Foxwell NT604) available that can read OBD2 codes, including TPS-related codes. And provide information on any issues detected with the TPS or other systems in the vehicle. Proper maintenance and timely replacement of a faulty TPS are crucial for the efficient operation of the engine and to prevent damage to other engine components.

Here is the interpretation of TPS-related codes so you can understand what’s wrong with your TPS when either of these codes shows up in your OBD-II scanner:

• P0120 or P0220: This code most likely appears when your TPS has malfunctioned.
• P0121 or P0221: This code most likely appears when the voltage given out by the TPS is unexpectedly out of range compared to the expected voltage range.
• P0122 or P0222: This code most likely appears when the signals given by the TPS are below the expected range of 0.5~0.1 Volts.
• P0123 or P0223: This code most likely appears when the voltage given by TPS is above the expected range of 4.5~5 Volts

Here are a few signs you may notice in your car due to a faulty TPS (while driving, despite having a check engine light):

1. Poor acceleration: If the TPS is not functioning properly. It can cause the engine to respond slowly or not at all when the accelerator pedal is pressed. This can result in poor acceleration and a lack of power.
2. Stalling or idling issues: A malfunctioning TPS can cause the engine to stall or idle roughly as the throttle opening is not properly regulated.
3. Incorrect shifting: The TPS also plays a role in controlling the transmission’s shift points. If the sensor is not functioning correctly. It can cause the transmission to shift at the wrong time, resulting in poor performance and increased wear and tear on the vehicle.
4. Reduced fuel efficiency: A faulty TPS can cause the engine to consume more fuel than necessary. Resulting in reduced fuel efficiency and increased emissions.

There are specific diagnostic tools and scanners available that can read OBD2 codes. Visit our store to see what OBD-II scanner fits best for your car’s needs.

Conclusion:

The throttle position sensor (TPS) is a component that measures the position of the throttle valve and regulates the air and fuel flow in the engine.

TPS’s proper maintenance and timely replacement are crucial to the engine’s efficient operation, better fuel consumption & achieving maximum power output.

TPS’s proper maintenance and timely replacement are crucial to the engine’s efficient operation, better fuel consumption & achieving maximum power output.

David Richard

Hey guys! I am David Richard, a renowned Mechanical Engineer and founder of Obd Core Scanner Review. I have 6 years of experience in the automotive section.