P2B97: exhaust valve learned endpoints outside their allowed windows

P2B97 checks offset in the exhaust throttle valve's SENT position feedback at its learned closed or open endpoints. The monitor does not simply compare a moving valve with its requested position. It asks whether the raw feedback at an endpoint lies in the expected window.

Two endpoint windows

The table permits a fully closed raw position from 4.80% to 14.70% and a wide-open value from 80.00% to 96.50%, using its “%5V” scale. A value outside either window meets the corresponding failure criterion. These percentages are feedback limits, not universal physical valve angles or connector voltages.

The diagnostic is associated with key-off learning and qualified end-of-trip operation. Conditions include an adequate battery supply for closed-loop control and valid temperature and valve information. The row states that no debounce is applied: the error can set the code when the applicable learning result is available.

What makes the evidence useful

Record which endpoint fails and the raw learned value. A closed-end offset, an open-end offset and a narrowed learned span are different observations, even though each may appear under the same generic code. Do not infer a broken motor simply because the learned sensor value is outside its window.

Confirmation needs a successfully completed applicable learning procedure, followed by acceptable endpoint values. Watching normal-looking motion with the engine running does not necessarily exercise a key-off endpoint check. The source does not establish a universal relearn sequence; use the exact vehicle's procedure.

Source and applicability

Documented 2025 GM gm-2025-04b monitor only; vehicle, engine and controller applicability must be established separately. GM monitor table, PDF page 1531; GM monitor table, PDF page 1532.