P0BC6: Battery temperature sensor E fails a stability check

P0BC6 names hybrid/EV battery temperature sensor E circuit intermittent/erratic. The 2018 GM controller evaluates how much the signal moves during a defined window. A large total movement can fail even when the starting and ending readings are similar.

The relevant calculation

The table specifies an integrated absolute change over ten samples, with a threshold above 10. Four failed evaluations among five are required, at 100 milliseconds per sample. It also requires system voltage above 10.2 V and no active battery-interface communication fault from the defined group. The listed reporting category is Type B, two trips.

This is not a comparison with the other temperature sensors or a direct overtemperature threshold. Treating it as either would skip the signal-stability issue that the code describes.

Evidence worth preserving

A technician should preserve the channel E trace and the state of the data source. An intermittent connection is one explanation expressly discussed by GM, but the monitor does not locate that connection. A later steady value cannot prove that the earlier erratic condition was absent.

Following the appropriate repair, verify a credible stable signal while the diagnostic is enabled. If another fault still blocks the monitor, no fresh code is not the same as a passing evaluation. Confirm sensor E's actual location through the vehicle documentation; internal pack work belongs to qualified high-voltage service.

Source and applicability

This explanation follows the documented GM monitor, not a verified application to every vehicle with this code. Confirm the vehicle, reporting module and calibration in current service information. GM diagnostic table, physical page 895.