Throttle Position (TP) Sensor

A malfunction in TP sensor circuit can set DTCs P0121-P0123. For testing and adjusting procedures, see THROTTLE POSITION (TP) SENSOR in ADJUSTMENTS article. Use the following procedure to diagnose TP sensor.

1. Insert a .14" (3.5 mm) feeler gauge between throttle stop screw and throttle lever. Check Idle Speed Control (ISC) motor plunger for contact with throttle lever screw. If ISC motor plunger is contacting throttle lever screw, engine must be brought to normal operating temperature.
2. Connect a Tech 1 or other OBD-II compatible scan tool to Data Link Connector (DLC). Turn ignition on. Using scan tool, read TP sensor voltage. If voltage is not 0.98-1.02 volts, adjust TP sensor. Loosen TP sensor mounting screws and turn TP sensor until voltage is as specified.