P048D: exhaust throttle SENT position feedback below range

P048D is a low electrical-range check of the exhaust throttle valve's SENT position feedback. The documented boundary is a raw position value below 1% of the 5 V scale.

Feedback validity differs from valve position

The threshold concerns the signal representation, not a rule that the valve must always remain above 1% opening. An invalid low raw value can compromise position interpretation without independently proving that the exhaust valve is mechanically closed.

The monitor also requires no SENT communication-loss fault. Establishing whether the receiver has a usable signal is therefore separate from deciding whether the received value is electrically plausible.

Confirm under enabled conditions

The source gates testing until cranking is over, with relay supply above 11 V and diagnostics enabled. It uses 480 failed counts among 600 samples on a 6.25 ms task and lists Type A, one-trip reporting.

For verification, demonstrate valid SENT communication and an in-range raw feedback value during an eligible assessment. A normal exhaust-pressure reading does not independently validate this position signal. The table does not provide a physical connector designation, pin voltage procedure or component-isolation result. Use the exact vehicle's service data to identify the sensor architecture and circuit before considering parts. Any access near the exhaust system must also account for its thermal condition.

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 1202.