Diagnostic Aids
WARNING: This page is about a different car, the 2002 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
If DTC P0121 is also set, resistance may exist in reference return circuit (Purple wire). Check for corrosion and for loose or spread terminals.
A skewed TP sensor No. 2 can set this DTC. Check voltage range of sensor using THROTTLE ACTUATOR CONTROL in SPECIAL FUNCTIONS section of scan tool, which will command throttle control module to move throttle plate. See THROTTLE ANGLE POSITION VS VOLTAGE table.
THROTTLE ANGLE POSITION VS VOLTAGE
| Throttle Position (%) | TP Sensor No. 1 Voltage | TP Sensor No. 2 Voltage |
|---|---|---|
| 0 | 0.50 | 4.45 |
| 7 | 0.82 | 4.17 |
| 25 | 1.45 | 3.55 |
| 50 | 2.45 | 2.55 |
| 75 | 3.35 | 1.65 |
| 100 | 4.25-4.62 | 0.70-0.16 |