The throttle position sensor (TPS) monitors, how far open the throttle valve is.

In other words, by how far down, the accelerator pedal has been pushed.

So, the wider it is open, the more air, is able to flow in. In contrast, the less that it is open, less air is able to flow in.

Advances in technology, have allowed the throttle position sensor (TPS) to work, without actually needing contact with the throttle.

So, the position of the throttle and how quickly it’s opening and closing, is transmitted to the (ECM). Consequently, the computer uses that information, to decide how much fuel, is injected into the engine and the spark timing.

What can happen when it malfunctions:

  • It can trigger a “check engine” warning light.
  • It causes the engine to, idle roughly, surge, hesitate or stall.

As a result, the engine control module (ECM), doesn’t know where the throttle position is. Therefore, it can not correctly, set the fuel mixture or ignition timing.

(TPS) Engine Codes, Include:

  • P0120 (TPS)/Switch A Circuit Malfunction
  • P0121 (TPS)/Switch A Circuit Range/Performance Problem
  • P0122 (TPS)/Switch A Circuit Low Input
  • P0123 (TPS)/Switch A Circuit High Input
  • P0124 (TPS)/Switch A Circuit Intermittent

Symptoms of a bad, (TPS) include:

  • Check engine light is on.
  • Engine hesitation or no acceleration.
  • Car bucks or jerks violently.
  • Engine surges and stalls out.
  • Engine starts and dies immediately.
  • Poor fuel economy.
  • Engine cranks, but fails to start.
  • Car goes into limp-home mode.

Replacing the throttle position sensor (TPS), can be straightforward, depending on the model. But, the hardest part of the procedure, is the diagnosis. Therefore, you will need to have, the proper diagnostic equipment.

So, it is a small sensor, that’s about the size of your key fob. Also, it has an electrical connector attached to it, that normally houses three wires. On most engines, there are two smaller screws, that secure it to the throttle body.

Resetting a (TPS)

So, there are many different methods you can use, to reset the throttle position sensor (TPS) on your car. And, that all depends on the car model you drive. On some car models, you can reset the throttle body sensor. by disconnecting the battery. While on others, you need to use a diagnostic tool, to reset and calibrate it.

NOTE: The (IAC) valve maintains the idle of the engine, when the accelerator pedal, causes the throttle plate to close. The two sensors that help feed into the (IAC) is the (RPM)’s of the engine and (TPS). As the (TPS) gets close to zero, the (IAC) starts to open. If the (TPS) stays at zero, the (IAC) is then positioned to maintain the normal idle (RPM)’s.

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Throttle Position Sensor (TPS) – Function – Failure – Testing

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