P233B: fuel metering valve 2 low-side short to ground

The cited P233B monitor belongs to fuel metering unit valve 2, although the generic title calls it fuel pressure regulator C. Its specific failure is a low-side control circuit short to ground.

Why the off-state matters

The controller evaluates voltage across the low-side driver while that driver is off. Voltage remaining low in this state is the fault evidence. The source relates the electrical classification to less than 0.5 ohm between the valve's low-side connection and controller ground. It is not a low-fuel-pressure threshold.

The enable conditions are powertrain relay voltage above 11 V, no engine cranking and active run/crank. The table specifies 100 ms sampling and Type A, one-trip reporting. Failure-count fields are empty, preventing a reliable calculation of detection time.

Diagnosis and confirmation

A low voltage can be expected in other commanded states, so a meter reading without driver-state context does not reproduce this monitor. The next useful evidence is the command state together with the electrical fault report, interpreted through the exact wiring procedure. Keep this diagnosis separate from P233C, which evaluates a high voltage during the on-state. Any high-pressure fuel-system intervention requires appropriate professional methods; this electrical summary does not call for opening fuel lines. Verify that the off-state diagnostic completes without the ground-short report after the identified defect is addressed.

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 817.