Circuit Description

TP sensor is a variable resistor mounted to throttle body which detects throttle opening angle. ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when ECM consistently detects less than .1 volt or more than 4.9 volts on VTA circuit. ECM will operate in fail-safe mode if DTC P0120 is set. Possible causes are:

• TP sensor circuit is open or shorted.
• Defective TP sensor.
• Defective ECM.