DTC P0121 - Throttle Position (TP) Sensor Circuit Range
- Install scan tool. Start engine and check if DTC P0121 is present. If DTC is present, go to next step. If DTC is not present, problem is intermittent.
- Check continuity of circuit between TP sensor and MAF sensor. See appropriate wiring diagram in WIRING DIAGRAMS section. Repair circuit as necessary. If circuit is okay, go to next step.
- Turn ignition off. Disconnect TP sensor harness connector. Connect an analog type ohmmeter between TP sensor terminals No. 1 and 3. Move throttle from idle to wide-open position. Ohmmeter needle should sweep smoothly, in proportion to throttle opening. If movement is not smooth, replace TP sensor. If movement is smooth, go to next step.
- Check MAF sensor. For further diagnosis, see related DTC or SYSTEM/COMPONENT TESTS article. Replace MAF sensor as necessary. If MAF sensor is okay, go to next step.
- Clear DTC. See CLEARING DTC(S) . Retest system. If DTC resets, replace ECM.