Throttle Position Sensor: Testing and Inspection

A scan tool displays throttle position in volts. The scan tool should display 0.20 volt to 0.90 volt with the throttle closed (as at idle) and ignition ON. Voltage should increase at a steady rate as the throttle opens. Voltage should be near 5.0 volts at wide open throttle.

A scan tool also has the ability to display the throttle angle and should display 0% when the throttle is closed, and increase smoothly to 100% at WOT. The Powertrain Control Module (PCM) has the ability to auto-zero the TP sensor voltage if it is below about 0.90 volt (900 mV). This means that any voltage less than 0.90 volt will be determined by the PCM to be 0% throttle. A fault in the TP sensor or circuit should set a DTC P0122 or P0123. A stuck sensor will set a DTC P0121.