P0846: pressure-sensor B performance combines pressure and ratio evidence

P0846 is pressure-sensor B performance in the cited CVT strategy. The controller compares requested and measured pulley pressure, then checks average variator speed-ratio error to support a plausibility failure.

A pressure difference alone is incomplete

The displayed criterion requires average speed-ratio error above 0.2000 together with pressure error above 500 kPa in steady state or above 1,500 kPa in nonsteady operation. Separate timing conditions apply to those states. It would be misleading to call every 500-kPa difference a confirmed P0846 event.

The enable conditions also require calculated line pressure above 600 kPa, vehicle speed above 35 km/h, the relevant high-side drivers on and credible supporting sensors. Related speed and pressure electrical faults can prevent this performance check from running.

The source's sensor naming is inconsistent

This performance row identifies the primary pulley, but the neighboring sensor-B low/high rows identify the secondary pulley. The article therefore explains the monitor without assigning a physical sensor location. Vehicle-specific service information must resolve that mapping.

Capture both pressure quantities and ratio error through the qualifying interval. Verification should show that the pressure/ratio relationship passes its actual enabled test, not simply that a pressure PID looks plausible at rest. This is evidence about sensor performance in the documented CVT, not a universal proof of failed mechanical pressure control or a mandate to replace a named pulley sensor.

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 1134. Neighboring rows documenting the mapping conflict: page 1137, page 1138.