P0B92: block 18 low depends on the block 19 report too

P0B92 is block 18 voltage measurement out of range low in this GM hybrid source. The circuit R label shown by a generic reader is not a complete description of the evidence needed. The neighboring block 19 reading participates in the diagnosis.

Capture both channels

The table requires block 18 below 2 V and block 19 below 2 V. A technician should preserve the pair and their operating context rather than diagnose from whichever low number remains visible later. The published rule does not say that either channel alone is sufficient.

Fifteen failing observations among twenty samples are required at a 100 ms interval. This counter distinguishes a repeated condition from a solitary scan update. The two-trip Type B reporting classification is a separate part of the monitor description.

Determine whether the controller could test

The BPCM must be in RUN, its 12 V supply must be within 9–18 V, and P0A1F must be inactive. If those prerequisites are not satisfied, a code that does not immediately recur has not necessarily passed its diagnostic check.

The low reports may guide a sensing-path investigation, but the summary does not identify a failed battery component or prescribe replacement. Match the actual hybrid system and use its service procedure to distinguish measurement integrity from real battery voltage. High-voltage access requires qualified personnel and the vehicle's isolation precautions.

Source and applicability

GM 2010 10OBDG10 Hybrid Diagnostics, cited BPCM or hybrid-controller monitor only. Historical calibration values are not universal specifications; no per-code model, engine or hardware fitment has been established. GM PDF, physical page 232.