5 Symptoms of a Bad Throttle Position Sensor (TPS) & Replacement Cost

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The throttle position sensor is a very vital part of the car engine.

For the engine to know how much acceleration you want and how much you give, it needs to measure the throttle body’s angle to match it with the fuel injection.

This article will discuss some of the most common symptoms when the throttle position sensor is damaged or faulty.

5 Symptoms of a Bad Throttle Position Sensor (TPS)

  1. Poor acceleration
  2. Idle surging
  3. Check engine light
  4. Sudden surge while driving at high speeds
  5. Problems with shifting gears

Because the throttle position sensor is such an important part of the engine’s performance, it could result in many different symptoms.

Here is a more detailed list of the 5 most common symptoms of a bad throttle position sensor.

Poor Acceleration

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One of the most common signs of a defective throttle position sensor is delayed or poor acceleration. Delayed acceleration means that there is a considerable time difference between stepping on the accelerator and the actual acceleration of the vehicle.

If you also notice that the car judders when accelerating, this can be due to a damaged throttle position sensor.

Idle Surging

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The term idling refers to the operation of the engine when the vehicle is not actually moving. If you notice that your engine fluctuates when idling, this may be due to an irregular air-fuel mixture, which is related to a faulty throttle position sensor.

If the ECM does not receive correct information from the throttle position sensor, the throttle will not function correctly, resulting in idle surging.

Check Engine Light

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There are several sensors in a vehicle, and if one sensor is not working, the check engine light comes on.

Although the check engine light will illuminate for various other reasons, it is advisable to check the throttle sensor, especially if your car has poor acceleration and idle surging.

If your check engine light is on and related to the throttle position sensor, it will most likely be a trouble code related to the sensor in the ECU. You can check it with an OBD2 scanner.

Sudden Surge while Driving at a High Speed

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If you have an electric throttle body, one of the most dangerous effects of a defective throttle position sensor is a sudden increase in speed while driving at high speed on a highway. What happens is that the throttle in the throttle valve may close automatically, and if the driver presses the accelerator pedal too hard, the valve suddenly opens and gives the car a small speed boost.

This happens if the throttle position sensor is damaged and sends an incorrect signal to the throttle valve, causing it to open and close suddenly.

Problem with Shifting Gears

Gear Shifter

A poor throttle position sensor causes a problem with acceleration, which in turn causes a problem with the automatic transmission.

The throttle position sensor does also sends information to the automatic transmission control unit. If this information is faulty, there might also be a problem with your automatic transmission’s shiftings.

The function of the throttle position sensor

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The Throttle Position Sensor (TPS) is an integral part of the vehicle’s fuel management system as it determines the angle of the throttle body flap.

The throttle position sensor transmits throttle position data to the engine control module (ECM), and this information helps determine how much fuel should be injected into the engine at the right time.

The throttle position sensor can fail for a number of reasons and, as a result, affect the performance and the fuel consumption of the car, it can drop significantly.

Throttle position sensor location

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The throttle position sensor is located on the throttle body since it is measuring the angle of the throttle body valve.

If you can see a sensor with wires to it in the same direction as the throttle body axle, it is most likely the throttle position sensor.

If you have a newer car with an electric throttle body, the throttle position sensor is most likely integrated into the throttle body and can’t be replaced separately.

Throttle Position Sensor Replacement Cost

The average throttle position sensor replacement cost is between 80$ to 300$, depending on the car model and labor costs. A throttle position sensor costs 30$ to 100$. The labor costs are usually between 50$ to 200$ at a workshop.

If your car has an electronic throttle body, it is possible that it is not possible to replace the position sensor alone – you have to replace the whole throttle body, which can result in an expensive cost of 100$ to 900$.

The price of the labor cost does vary heavily depending on the car model since, in some cars, you can change it within 5 minutes, and it can take several hours on others.

Remember that after you replace a throttle position sensor or the throttle body, you need to reprogram/recalculate the throttle angle. This can often only be done with the right diagnostic tools.

Written by: Magnus Sellén

Founder, owner & main author of Mechanic Base. I have been repairing cars for more than 10 years, specialized in advanced diagnostics & troubleshooting. I have also been a drifting driver and mechanic for over 7 years.