Diagnostic article Generic OBD-II
P2728: Solenoid performance includes current, switching frequency and duty agreement
Learn the three electrical checks behind P2728 and why it should not automatically be treated as a hydraulic pressure failure.
Read before applying this article
Documented application
2025 GM 25OBDG06C 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.
P2728 supervises electrical performance of a pressure-control solenoid in the cited GM transmission. The generic definition calls it solenoid E, while this document labels its monitored channel PCS 1. That naming relationship must be resolved for the actual transmission before locating hardware.
Three ways the electrical behavior can disagree
The current branch compares commanded and measured current; an absolute difference of at least 100 mA lasting at least one second is a failure. This is an electrical tracking measurement, not a direct reading of hydraulic pressure.
A separate branch checks switching frequency against the energized state. The expected frequency behavior changes when the solenoid is off. A further plausibility branch compares commanded and controller-measured duty cycle, with a persistent disagreement criterion. A generic “performance” label can therefore represent different underlying evidence.
Avoid evaluating the test during a transition
The current check requires valid supply and driver conditions, absence of relevant electrical faults, and a transmission that is not shifting. Lockup engagement and certain neutral-control operations also affect eligibility. Those restrictions matter when reviewing a trace captured during a gear change.
Preserve the failed branch, command, electrical response and operating mode together. A correct current at one instant does not validate switching-frequency or duty agreement. The source supports distinguishing electrical performance failures, but does not identify a blocked valve or justify replacing a solenoid solely from the code.
Source and applicability
2025 GM 25OBDG06C 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. 25OBDG06C, PDF page 1299. 25OBDG06C, PDF page 1300.
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
Pressure Control Solenoid E Control Circuit Range/Performance
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