P0458: Purge-solenoid control output low while the driver is off

P0458 is the EVAP purge-control circuit-low code. The cited GM low-side driver diagnostic looks for short-to-ground feedback with the canister purge output powered off. It is an electrical check; it does not directly measure unwanted vapor flow.

Why command state matters

The controller compares off-state voltage with its internal acceptable range. Its short-ground specification corresponds to impedance below 0.5 Ω between output and controller ground. That specification belongs to the driver design and is not an instruction to measure resistance on a powered circuit.

The monitor requires powertrain-relay voltage above 11 volts and counts twenty failures in twenty-five samples, at 250 milliseconds per sample. It is Type B with two-trip reporting in this table.

Overlapping fault labels

The source notes that P0443 may also be set by some controller implementations. A paired low/open report is therefore not enough to declare two independent faults. Identify the actual driver architecture and preserve both code statuses before following the circuit procedure.

Verification should demonstrate that the off-state feedback remains acceptable during a completed test. A purge valve that appears to flow correctly under a manual command does not independently verify its off-state electrical monitoring. The source provides no universal pinout or replacement rule; use the applicable FTZM/ELCP vehicle procedure to localize the condition.

Source and applicability

This explanation is limited to the 2025 GM 25OBDG03A monitor on page 297. Its thresholds are calibration examples, not universal specifications. Confirm the vehicle, engine and controller procedure before applying them.