Diagnostic article Generic OBD-II
P074F: seventh gear fails the commanded engagement process
P074F is the inability-to-engage-seventh-gear code in the cited transmission table.
Read before applying this article
Documented application
2025 GM 25OBDG07A Part2 diagnostic monitor documentation; the application-matrix filename mismatch is unresolved, so no model or engine applicability is inferred.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
P074F is the inability-to-engage-seventh-gear code in the cited transmission table. Its diagnosis concerns a sequence of unsuccessful engagement attempts, not an assessment of whether the vehicle should normally use seventh gear at a particular road speed.
Conditions before an attempt counts
The seventh-gear request and engagement-active state must exist, with system pressure above 4.5 bar. The application must not be in its error or bypass states. Four failed engagement attempts are required for confirmation.
Failure may arise from excessive initial synchronizer differential speed, excessive speed difference in an engagement state, or expiration of a state timeout without the required transition. The initial limit includes a calibrated base plus 250 rpm; the base and subsequent limits are not supplied as standalone numbers on this page.
Interpreting the evidence
A missing seventh-gear command is different from a command that begins but fails. The former does not recreate the requested-and-active conditions of this diagnostic. Likewise, the attempt counter should be interpreted with the state where progress stopped.
Verification should confirm that an eligible seventh-gear engagement completes using the proper transmission procedure. The table does not establish a road-test speed, physical gear location, or replacement part. It explains the controller’s evidence and the distinction between missing command and failed execution.
Documentation and applicability
These details describe the monitor in GM’s 2025 25OBDG07A Part2 file. Its application-matrix filename does not match the download index, so model and engine applicability remain unresolved. Use the vehicle’s correct service information before applying these calibration details.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
Unable To Engage Gear 7
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT