Diagnostic article Generic OBD-II
P26A9: a failed coolant-bypass endpoint learn needs its fault context
The GM P26A9 monitor includes failed endpoint learning and failure to reach a commanded valve position after controlled relearn attempts.
Read before applying this article
Documented application
GM 2015 15OBDG01 HCP2/VICM coolant-bypass valve monitor. Only the cited monitor and calibration are described; per-code vehicle and engine applicability has not been established.
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.
P26A9 concerns the coolant-bypass valve's endpoint or movement performance in this GM hybrid-control document. The table describes both a failed end-position learning request and a valve that does not reach its commanded position. Neither description is a direct instruction to replace the valve without checking its prerequisites.
Learning failure and invalid feedback are different
The endpoint-learning branch requires an active propulsion system, adequate system voltage and coolant temperature above 50°C. Relevant valve circuit, position-signal and coolant-temperature faults must not be active. A learning result obtained with an invalid input should not be treated as the same enabled test.
The source also describes an unsuccessful commanded movement followed by up to three relearn attempts, then another assessment of whether the position was reached. The sequence matters; a snapshot showing requested and actual positions apart does not establish that the entire documented process has failed.
Preserve what the controller attempted
Useful records include the learn-request result, commanded and actual positions, associated circuit status and the operating conditions. Those data distinguish a failed learning operation from a position discrepancy observed before the relevant test could run.
The document does not authorize repeated manual relearns as a substitute for diagnosis, nor does it provide universal disassembly or coolant-handling instructions. Use the actual vehicle's procedure and thermal-system precautions. Confirmation should establish a successful required learning state and credible commanded movement, with the original complaint resolved, rather than only an erased P26A9 record.
Source and applicability
GM 2015 15OBDG01 HCP2/VICM coolant-bypass valve monitor. Only the cited monitor and calibration are described; per-code vehicle and engine applicability has not been established.
15OBDG01 Hybrid Diagnostics, physical PDF page 567.
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
Engine Coolant Bypass Valve A Position Sensor Stop/Minimum Stop 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