P072D: Second gear can be declared stuck after repeated neutral requests

P072D is the stuck-in-second-gear code. The documented GM monitor focuses on unsuccessful disengagement, so its evidence concerns leaving second gear for neutral rather than failing to enter second gear.

The feedback path is part of the diagnosis

The row identifies shift-fork position sensor 4 for the electrical or consistency-fault branch during the shift. It also allows a state-transition failure with the actuation timer reaching a calibrated timeout. Neither branch alone proves that a gear tooth or synchronizer is physically seized.

Second-gear disengagement must be both requested and active, with system pressure above 4.5 bar. The application must not be in its error or bypass state. The fault is confirmed after at least four failed disengagement attempts.

Read the sequence rather than the final gear display

Preserve the request to leave second, the sensor-4 status and the failed-attempt history. A dashboard display still showing second gear does not reveal whether the command failed mechanically, the feedback became inconsistent, or the sequence timed out.

The monitor shares its general method with other stuck-gear codes, but P072D selects the second-gear sequence and its documented feedback branch. Exact transition criteria require the referenced calibration information. Use the applicable transmission service process; do not force repeated shifts merely to reproduce the count or interpret the code as an automatic transmission-replacement instruction.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 1040.