P049D: high-pressure EGR closed-stop learning is outside its window

P049D evaluates high-pressure EGR position-sensor offset during key-off learning. The cited SENT implementation checks the raw signal when the valve reaches its fully closed learning position.

A learned endpoint has a narrower window

Failure is a closed-position raw value below 5% or above 12.70% of the 5 V scale. Those are endpoint-learning limits, not the broad electrical-range boundaries used for circuit-high or circuit-low faults. A signal can be electrically plausible yet unsuitable as the learned closed reference.

The procedure requires successful key-off learning, coolant between 30°C and 150°C, outside air at least −40°C, valid temperature inputs and battery voltage at least 9.50 V for closed-loop position control. The source also requires the end-of-trip event to have elapsed and diagnostics to be enabled.

Interpret key-off results correctly

A running-engine position check does not reproduce this assessment. Establish that the learning sequence actually completed and identify which side of the closed-stop window failed. Those two observations are more useful than assuming the general position display proves a correct offset.

The table applies no extra debounce after the error exists and lists Type A reporting. Verification should establish an acceptable learned endpoint through the applicable service procedure. It does not prescribe manually forcing the stop, adjusting a sensor or replacing the EGR assembly solely from the code.

Source and applicability

2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately. These tables describe detection logic, not a complete repair procedure or a component replacement verdict. gm-2025-04b, PDF page 1205; gm-2025-04b, PDF page 1206.