P25B3: Why wastegate A stuck-open depends on position normalization

The cited P25B3 monitor classifies the bank-one wastegate as jammed open only after a substantial control deviation persists. The source describes deviation outside a ±40% band and timing longer than one second. Position is then used to decide which side of travel the jam represents.

The percentage has a configuration context

The table contains two cases governed by whether zero-percent actuator position means closed. With that status false, its open classification uses position below 50%; with it true, position above 50%. Treating a displayed percentage as a universal physical opening would reverse the diagnosis in one configuration.

Make verification comparable

The actuator must be active, while an actuator test and initial end-stop learning are not active. Other eligibility conditions exclude a disabled power stage and a frozen-actuator cold-start condition. Those gates make a commanded workshop test different from an automatically eligible driving event.

Record requested versus observed behavior, the normalization status and whether the jam check actually ran. The result supports ineffective position control with an open-side classification; it does not by itself separate a mechanical obstruction from every possible actuation or feedback fault. Model-specific service information is still needed for component isolation.

Document scope and source

2025 GM 25OBDG07A Part 2 documented monitor only; its application-matrix filename join is unresolved. No model, engine or universal calibration applicability is inferred. These figures explain the cited controller logic, not a vehicle-specific repair instruction. Match the vehicle’s service information before applying them.

GM physical PDF page 865, GM physical PDF page 866.