P0848: pressure-sensor B high input is a signal-encoding problem

P0848 is transmission pressure-sensor B circuit high. The cited CVT monitor checks raw PWM duty cycle above 95 percent and describes voltage-short or open-circuit failure modes.

High signal is not a mechanical pressure diagnosis

The failure boundary is the fraction of signal on-time, not kPa or a universal pressure limit. Treating this code as proof that transmission pressure is too high would confuse electrical encoding with the physical quantity the sensor normally measures.

The source requires more than 0.3 second of failure within a 0.5-second sampling window. It also requires battery and run/crank supplies above 9 volts for the documented short enable interval. A single pulse measurement should therefore be interpreted with timing and supply context.

Sensor identity remains bounded

The electrical row identifies a secondary-pulley sensor, while the neighboring P0846 sensor-B performance row describes the primary pulley. This inconsistency must be resolved with the specific transmission's wiring and service information before choosing a physical component.

Capture the raw signal, controller identity and diagnostic status. Verification should establish a passing electrical monitor and valid signal encoding before relying on calculated pressure for further performance tests. The table does not distinguish every open-path fault from every voltage-short fault, and it does not prescribe replacing the sensor. The unresolved naming issue is retained explicitly; no physical test point or model compatibility is inferred from the generic B designation.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 1138. Neighboring rows documenting the mapping conflict: page 1134.