P2381: low-pressure EGR differential-pressure signal high

P2381 is called EGR sensor D circuit high in the generic dictionary. The GM table identifies a low-pressure EGR differential-pressure sensor and checks its raw voltage representation against an upper electrical boundary. The failure threshold is above 99.83% of that representation; it is not an EGR pressure limit in kilopascals.

Qualification and timing

The test must be enabled by calibration, the diagnostic system must be active, and engine cranking must have ended. Powertrain relay voltage must exceed 11 V. The controller counts 480 failed observations out of 600 at a 6.25 ms task rate, with Type A, one-trip reporting.

What this changes in diagnosis

Keep a pressure reading separate from the raw signal used for this decision. Concluding that EGR pressure is excessive from the code's word “high” skips the electrical-range test the controller actually performed. Also preserve the signal's scale; a percentage from the table cannot be used directly as a terminal-voltage specification.

For confirmation, establish that the electrical-range monitor ran after cranking under qualified supply conditions. A plausible pressure display alone may not expose the raw-input fault. Circuit identification and any terminal measurements must use the exact vehicle's service data rather than an assumed five-volt conversion.

Source and application limits

This explanation covers the cited 2025 GM monitor. Confirm the vehicle and calibration in its service information before applying these limits; inclusion in this file does not establish model compatibility. GM diagnostic parameters, PDF page 1447.