P02CC: cylinder 1 reaches the minimum injection-learning limit

P02CC concerns the lower limit of cylinder 1's learned injector energizing-time correction. In the cited diesel strategy, Small Quantity adjustment based on rail Pressure drop (SQP) learns from a small commanded injection during fuel cut-off.

What reaches the limit

The controller estimates injected quantity from the fuel-rail pressure drop and evaluates the newly learned time correction against a calibrated minimum. The table names the limit in microseconds but supplies no universal numeric value. “Minimum” therefore does not mean that rail pressure itself is below a stated pressure threshold.

The result is stored separately for the SQP rail-pressure levels. One saturated entry can set the diagnosis; the described unset condition requires every entry to be free of saturation. A normal result at a single pressure level does not settle the whole map.

Useful diagnostic evidence

Check whether SQP authority diagnosis and SQP injection management were enabled when learning occurred. The table ties evaluation to learning and cylinder firing events, rather than giving a fixed elapsed-time completion test. This matters when a short drive produces no new result.

A useful investigation separates the stored cylinder-1 correction from the pressure-drop evidence used to calculate it. That is diagnostic reasoning from the monitor design, not an OEM instruction to replace an injector. High-pressure fuel work requires the applicable professional service procedure.

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 1137.