P0796: CVT line-pressure performance compares both pulley pressures

P0796 is pressure-control solenoid C performance/stuck off. In the cited CVT monitor it concerns line-pressure control and compares the pump-related commanded pressures with measured primary and secondary pulley pressures.

Both pressure differences participate

The short-term branch requires commanded-minus-measured error above 1,000 kPa on both pulleys. Failure time beyond 0.2 second updates a short-term counter, which must exceed three. One low pulley reading without the matching error on the other does not reproduce this specific branch.

A separate long-term branch uses bounded differences above 500 and below 2,000 kPa on both sides, with a longer failure-time decision. These paths make a single universal pressure-error threshold misleading.

Supporting pressure measurements must be valid

The monitor excludes specified low-circuit solenoid faults and pulley-pressure sensor electrical faults. It also requires the shared high-side drivers on and calculated line pressure above 600 kPa, with appropriate engine/hydraulic conditions. A defaulted sensor reading or disabled driver changes the evidence substantially.

Record both commanded and measured pulley pressures, diagnostic prerequisites and which failure path completed. This comparative pattern is stronger evidence than an isolated line-pressure complaint, but it still does not uniquely prove a defective solenoid C. Verification should demonstrate adequate pressure response and a passing applicable monitor through the exact CVT service procedure. The source does not provide physical pressure-test ports or a transmission teardown instruction.

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 1120.