Circuit Description

The TP sensor is a variable resistor that monitors throttle opening. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. Code is set when ECM consistently detects less than .1 volt from VTA circuit and closed throttle position switch is off. Code can also be set if ECM consistently detects 4.9 volts or more. Code P0120 will not set if there is an open in IDL circuit. Possible causes are:

TP sensor open or short circuit.
TP sensor malfunction.
ECM malfunction.

NOTE: If Codes P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article.