P02D6: cylinder 6 reaches a lower SQP adaptation boundary

P02D6 is the lower-limit SQP learning code for cylinder 6 in the cited GM table. The controller evaluates whether a newly learned injector energizing-time delta is below the minimum allowed calibration.

Distinguish learning from circuit monitoring

The strategy estimates small injection quantity from a pressure drop in the rail during diesel fuel cut-off. Its output is a time correction. A low correction limit is therefore a different observation from low voltage at the injector driver, and the source does not equate the two.

SQP retains saturation results at the defined rail-pressure levels. One stored saturated result can set the condition; the unset description requires every stored result to be nonsaturated. A diagnostic review should identify the affected learning region instead of assuming all cylinder-6 operation is equally affected.

Verify that new evidence exists

SQP injection management and the authority diagnosis must be enabled. The monitor's completion time follows the SQP learning process, with evaluation associated with cylinder firing events. If learning did not run, a drive without a returning code adds limited evidence.

The page specifies Type B, two-trip reporting and a calibration-dependent limit in microseconds. It contains no universal offset target, guaranteed symptom or failed-part conclusion. Assess the learned values and their pressure-drop basis using applicable service information, and leave high-pressure fuel access to an appropriate professional 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 1157.