Diagnostic article Generic OBD-II
P27F2: Range-position circuit high is not a request for a higher gear
Understand the high-voltage boundary and eligibility behind the mode-valve B position-sensor P27F2 monitor.
Read before applying this article
Documented application
2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment 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.
P27F2 concerns excessive raw voltage on the transmission mode-valve B position-sensor circuit. Its high designation is electrical and has no direct meaning of a higher gear or a more open hydraulic valve. The cited GM diagnostic classifies the condition as a short toward voltage.
Compare the raw signal with its own boundary
The failure limit is above 2.538 V in the documented internal electronic range-selection arrangement. P27EF supervises a separate invalid middle band, while P27F1 supervises the low end. These code distinctions are more informative than simply reporting that a range value looks implausible.
Battery voltage must exceed 8 V for more than one second and the diagnostic must be enabled. The source labels the implementation for GF9 and CVT systems; that scope cannot be extended to another transmission solely because the scanner displays the same generic code.
Determine whether the high value persisted
The monitor requires 0.100 second within a 0.163-second observation period, with a 6.25 ms update. Retaining the signal trace and enable state is therefore more useful than comparing isolated readings taken before and after a range change.
The classification does not locate the source of unwanted voltage or establish that the position sensor itself failed. A matching circuit procedure is needed to separate wiring, supply interaction and controller interpretation before making a component decision.
Source and applicability
2025 GM 25OBDG03B documented monitor only. Vehicle, engine and calibration applicability must be confirmed from the matching service information; no model fitment is inferred. These criteria explain controller logic, not a complete repair procedure. 25OBDG03B, PDF page 1697. 25OBDG03B, PDF page 1703. 25OBDG03B, PDF page 1704.
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
Transmission Range Control B Position Sensor/Switch Circuit High
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