P2CE7: downstream pressure raw signal below its electrical range

P2CE7 is an electrical low-range diagnosis for the downstream relative-pressure sensor. The controller compares its raw signal with the sensor's low clamp specification. The cited table associates a raw value below 0.02% with a short-to-ground classification.

Signal range and exhaust pressure are different

The threshold is expressed on the raw signal scale. It is not an exhaust-pressure limit of 0.02 kPa and does not establish that pressure in the exhaust is abnormally low. A genuine no-flow condition should still produce a valid sensor baseline rather than automatically become an electrical range failure.

Confirmation requires 158 failed observations out of 200 samples at a 12.5-millisecond task rate. The monitor needs active run/crank supply and ignition within range, but the engine itself must not be in the cranking phase. Diagnostic reset must also be inactive.

Use the correct fault classification

Review the raw channel and supply qualifications before drawing conclusions from a converted pressure display. A scan tool may show a substituted pressure when the electrical input is invalid. The ground-short classification guides the electrical investigation but does not identify the exact damaged wire, connector or sensor element.

Verification requires an in-range raw signal and completion of the electrical monitor under its enable conditions. Pressure-response and offset checks may be needed separately if the signal returns to range but remains implausible. The table does not support condemning a particulate filter from P2CE7 alone.

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 886.