What does a Throttle Position Sensor do?

The throttle position sensor is mounted on the air intake system's throttle body. The throttle body uses the input of the accelerator pedal to determine how much air should enter the engine. The throttle plate inside the throttle body opens as you press the accelerator, the more you press the pedal the more air will enter the engine.

The throttle position sensor identifies the amount of air entering the engine from the position of the throttle plate. As the sensor detects movement, it sends an electronic signal to the engine's computer (ECU) which processes the information (together with information from other sensors).

The computer adjusts the spark timing and fuel delivery to optimise the air / fuel mixture and combustion. In cars with an automatic transmission it also adjusts the converter clutch operation to control the shifting of the gears.

How do you know there is something wrong with the Throttle Position Sensor?

• When the engine idles rough.
• If the engine hesitates under acceleration.
• When the engine's performance is not as strong as usual.
• When the 'Check Engine' light on your dashboard is on.
• Provided the car has an automatic transmission, it might not change gear.

When should you consider a Throttle Position Sensor replacement?

Over time, the throttle position sensor can wear or fail. For example due to the intense heat and temperature fluctuations in the engine bay and, moreover, due to the sensor's continuous contact with the sensor wiper arm.

A malfunctioning throttle position sensor can lead to a variety of problems. From a lean or rich running engine, to the engine failing an emissions test to the automatic transmission not shifting gear correctly. It is therefore important to service the throttle sensor as and when stipulated in the guidelines set out by your car's manufacturer.

Should you experience problems with a throttle position sensor, then it is advisable to have it inspected and, if necessary, have the sensor replaced.

What happens during a Throttle Position Sensor replacement?

• The mechanic will read the ECU for possible fault codes related to the throttle body and sensor.
• The mechanic will inspect the sensor and ancillaries (like the electrical connectors).
• If necessary, the mechanic will replace the sensor.
• The mechanic will clean up the dirt inside the throttle body.
• The mechanic will advise if other components need to be replaced as well.
• The mechanic will re-adjust idle speed on the throttle body to factory stipulations.
• The mechanic will check the throttle and sensor and establish whether it works correctly.
• The mechanic will test drive the car.
• If necessary, the mechanic will make adjustments.

How much does a Throttle Position Sensor Replacement cost?

The cost of replacing a throttle position sensor depends on your car and what parts your car's manufacturer recommends using for the replacement. Find out what you could save by having the throttle position sensor replaced by ClickMechanic, by selecting your car at the top of this page!