P0965: CVT primary-pulley control is checked against ratio response

P0965 is pressure-control solenoid B performance. In the cited CVT monitor, B controls primary-pulley pressure. The diagnostic compares measured pressure with requested pressure and uses variator ratio error as supporting evidence.

Pressure error is interpreted differently during transitions

The shown thresholds are pressure error above 500 kPa in steady state or above 1,500 kPa outside steady state, combined with average speed-ratio error above 0.2000. A transition therefore has a different pressure-error boundary from stabilized operation.

The ratio condition helps avoid interpreting a pressure disagreement entirely in isolation. A diagnostic record should retain requested pressure, measured primary pressure and requested/measured ratio from the same event, rather than combine unrelated snapshots.

Do not borrow an electrical repair conclusion

Unlike P0964, P0966 and P0967, this row is a performance comparison, not an open, ground-short or voltage-short decision. A stored P0965 does not independently prove one of those electrical fault modes.

The source lists separate timing paths for steady and nonsteady ratio error, with additional delay conditions. Exact verification must follow the complete applicable CVT procedure, including its enabled state and valid engine-speed prerequisites. A single acceptable pressure reading after clearing does not demonstrate that the pressure/ratio comparison completed. The summary supports the primary-pulley performance interpretation but not a universal solenoid replacement, fluid-service remedy or model compatibility claim.

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 1146.