How to Tell If You Have a Faulty Throttle Position Sensor

February 21, 2012

Learn the eight telltale symptoms of a defective throttle position sensor, and how to test it.

Throttle Position Sensor

The throttle position sensor in your engine transmits information about the position of your throttle to the electronic control module or ECM. It consists of mechanical parts which may become worn and require replacement. A malfunctioning throttle position sensor will relay bad data to your car's computer and usually result in poor fuel economy. Knowing the symptoms of a defective throttle position sensor can help you quickly diagnose the problem and make needed corrections.

Symptoms of a Faulty Throttle Position Sensor

  • An unexplainable bucking and jerking in the vehicle
  • Sudden idle surges
  • Sudden engine stalling without any apparent reason
  • Hesitation while accelerating
  • Sudden surges in speed while driving on the highway
  • Intermittently flashing of check engine light for no apparent reason
  • Difficulties in changing gears
  • A drastic drop in fuel economy

How to Test a Throttle Position Sensor
You can use a standard ohm meter to test a switch and combination type throttle position sensor and a volt meter to test a throttle position sensor that uses a potentiometer. Check the resistance in various accelerator pedal positions, record the resistance and compare against values listed as acceptable in a quality car repair manuals such as Chilton or Haynes to determine whether or not the sensor needs to be replaced.

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