P0BAB: Sense W low is qualified separately from an open line

The cited 2015 GM battery controller reports P0BAB when the W cell-voltage reading is at or below 0.2 volt. This is a measurement-limit diagnostic. It is not the same test as the neighboring P0BA9 open-sensing-line code.

Preserve the exclusion information

The low-voltage monitor requires the listed open-sense-line faults to be absent. It also excludes sensing-module communication, balancing and internal-performance faults, and the secondary protection self-test must not be active. Consequently, a record of those companion conditions is necessary to judge whether the low-reading check was eligible.

These restrictions should not be converted into a conclusion that a cell is healthy whenever P0BAB does not repeat. An inhibited monitor may not be providing a fresh result.

What the timing establishes

The low reading must occupy 1.4 seconds of a two-second window. A single scanner update below the threshold is less information than the controller's qualified finding. Keep the recorded voltage behavior and operating-state history for the diagnostic technician.

The source's 0.2-volt value is specific to this controller and measurement architecture. It does not provide a universal battery-discharge specification, repair price or physical location for W. Any investigation of the battery and its sensing connections should follow the actual high-voltage service procedure. The next useful decision is whether the reported low measurement is trustworthy and reproducible under valid prerequisites.

Source and applicability

15OBDG01 Hybrid Diagnostics, cited controller and monitor only. Historical calibration limits are not universal specifications; per-code vehicle, engine and hardware applicability must be verified.

GM source, physical page 628.