P26A6: coolant-bypass valve feedback is below its electrical range

P26A6 is a low feedback-circuit fault for the coolant-bypass valve in this GM hybrid-control table. The controller is evaluating the electrical position signal. The result should not be translated directly into “the valve is fully closed” or “coolant flow is too low.”

The threshold is relative to a reference

The documented low criterion is feedback below five percent of the reference voltage. It must be present in 40 of 50 samples taken every 100 milliseconds, with system voltage above 10.2 V. The normalized percentage is not a stand-alone physical opening measurement or a universal pin voltage.

Preserve the feedback trend and supply conditions. One brief sample below the boundary is not the complete persistence test, while a stable-looking position value recorded after the event may conceal an earlier circuit interruption.

An invalid signal affects other valve diagnoses

The same source excludes P26A6 from certain valve movement and position-performance checks. That relationship means a low-circuit fault can prevent those checks from using the feedback as valid evidence. It does not independently prove that the valve mechanism is stuck.

Use the exact vehicle's circuit and thermal-system procedure to identify the reference, signal and associated connections. The table supplies no automatic actuator replacement decision and no safe disassembly instructions for a pressurized or hybrid thermal system. After correction, verify credible feedback and then establish whether the valve's separate movement or learning tests can complete normally.

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 pages 567, 568.