P02CE: understanding cylinder 2 minimum SQP authority

P02CE records a lower-bound learning problem for cylinder 2 in the documented SQP injector strategy. It is triggered by an energizing-time correction below a calibration-defined minimum, not by a low-voltage injector circuit reading.

How the controller obtains the evidence

During diesel fuel cut-off, SQP commands a small injection and estimates the resulting quantity from rail-pressure drop. Whenever it enters a learned value in the map, it evaluates that value against the minimum correction limit. The threshold has microsecond units, so converting this fault into a fuel-pressure limit would misread the table.

The controller retains a Boolean saturation result across the defined rail-pressure levels. At least one failing entry is sufficient for the diagnosis, whereas the described reset of that condition requires all entries to pass.

What changes the next check

First establish that cylinder-2 learning actually ran with SQP management and authority monitoring enabled. Second, distinguish a single affected pressure region from saturation across several stored regions. Those observations describe different patterns of evidence even though either can produce the code.

The source gives Type B, two-trip reporting, but no replacement rule or universal correction number. A service assessment must reconcile the learned value with the pressure-drop inputs and the vehicle's calibration. Opening a pressurized fuel system is not a diagnostic step supported by this summary table.

Source and applicability

2025 GM 25OBDG04B diagnostic parameter tables; the cited monitor only. Vehicle, engine and calibration applicability must be confirmed separately. These tables describe detection logic, not a complete repair procedure or a component replacement verdict. gm-2025-04b, PDF page 1141.