DH1 - Check for Other DTCs

Diagnostic Trouble Code (DTC) 121 indicates the Throttle Position (TP) sensor's rotational setting may be out of Self-Test range.

Possible causes:

- Binding throttle linkage.

- TP sensor may not be seated properly (tightened down).

- Damaged TP sensor.

- Damaged Powertrain Control Module (PCM).

- Check for DTC 327 in Key On Engine Running Self-Test.

- Is DTC 327 present with Code 121?

Yes -- Return to EEC-IV Diagnostic Trouble Code Charts and proceed as directed with DTC 327. Manufacturer Code Charts

No -- Go to DH2. DH2 - Check For Stuck Throttle Plate