P2048: first DEF valve has a low-side short-to-ground indication

P2048 concerns the low-side electrical control of reductant dosing valve 1. The reviewed GM strategy sets the code when the hardware interface reports a ground-short fault. It does not establish inadequate DEF quality or an injector flow restriction.

Interpret the status before selecting a repair

The ground-short diagnosis must be determinate before the monitor is eligible. This matters because an unavailable hardware result is not the same as a passed electrical test. The row gives no external pin-voltage or resistance threshold, so the short-to-ground interpretation comes from the controller's hardware diagnosis rather than a universal meter specification.

Power-state requirements allow key-on or engine-running operation, but exclude cranking. Battery voltage must exceed 11 volts and calibration must enable the check. A startup-related voltage disturbance outside that window cannot simply be equated with the monitor's qualified fault.

How it becomes reportable

The counter requires 30 failures in a 60-sample window at 100-millisecond intervals. Type A, one-trip reporting is listed. These details distinguish a repeated electrical condition from a single transient sample.

Verification should confirm that valve 1's ground-short status becomes valid and remains nonfaulted under the enabled conditions. A passing pump or pressure test answers a different question and cannot independently clear the valve-control diagnosis. The source does not identify whether the valve, connection or control path needs repair. Exact component identification, isolation and vehicle applicability require the appropriate service information for this 2025 GM strategy.

Source: GM monitor, PDF page 775.