P02CA: Overboost compares pressure with a changing request

P02CA concerns an overboost condition on bank 2. The GM monitor compares desired pressure with measured pressure upstream of the throttle, rather than setting the code whenever a single fixed boost number appears on a scan tool.

The difference limit is mapped

The table gives a pressure-deviation threshold in the range of 200–750 hectopascals and points to lookup table 78. That range represents calibration-dependent logic, not permission to choose whichever endpoint matches a test result. The condition must persist for at least 1.5 seconds.

The bank 2 sensed-value status must be valid, and an enabling control bit must be set. Two-trip reporting is listed. A pressure signal that has already failed its validity checks does not provide the same evidence as a valid signal showing excessive control deviation.

Compare like with like

Preserve the requested and measured pressure channels together, with their units and reference convention. A displayed pressure alone cannot show the size or duration of the controller’s error against its current target.

The summary labels the condition overboost but does not fully define the signed subtraction convention or the lookup-table selection in this row. Use the applicable calibration before reproducing its numerical test. The evidence narrows the problem to boost-control behavior; it does not identify a wastegate, actuator, sensor or turbocharger as the failed component from the code alone.

Source and applicability

This explanation covers the cited GM monitor, not every vehicle carrying this code. The application-matrix filename does not resolve cleanly to this file, so no model or engine fitment is assigned. GM diagnostic table, PDF page 823.