P0475: exhaust throttle open circuit with an off-state driver

P0475's generic exhaust-pressure-control label covers an electrical open-load test in the cited GM monitor. The target is the exhaust throttle valve command circuit, abbreviated ETV in the source.

What is detected

With the H-bridge driver off, hardware reports a load resistance above 200 kilohms. The valve must be requested away from its fully open default. This command prerequisite prevents the normal default position from being mistaken for proof of an open circuit.

The test also requires completion of cranking, relay supply above 11 V, enabled diagnostics and a determinate hardware error status. It uses 240 failed counts among 300 samples on a 12.5 ms task, with Type A reporting.

Distinguish electrical loading from exhaust pressure

Despite the code title, this row does not compare an exhaust-pressure sensor reading with a pressure limit. It assesses whether the actuator's electrical load appears connected. A pressure complaint alone does not establish the same fault signature.

Verification should confirm normal off-state loading in an eligible request context using the vehicle-specific electrical procedure. The resistance threshold is not an instruction to test a live circuit with an ohmmeter. The source does not isolate an open wire, connector, actuator or controller and provides no direct replacement instruction. Physical exhaust-system work also requires suitable handling of hot components.

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 1195.