P2B93: Bank 1 wastegate feedback outside its learned closed-stop band

P2B93 checks the bank 1 wastegate feedback at a specific mechanical reference: the fully closed stop. In the cited strategy, the controller evaluates the average feedback voltage calculated at that stop. A position reading captured elsewhere in travel does not test the same condition.

The closed-stop comparison

The documented failure band is an average above 3,768 mV or below 2,866 mV. The actuator must be completely closed for 300 milliseconds. Battery voltage must be at least 9,000 mV, and the source gives an engine-temperature operating range plus separate diagnostic inhibitors.

This is why raw range validity and learned-stop plausibility should be kept separate. A sensor may produce an electrically readable signal while its closed-stop reference falls outside the accepted band. On the other hand, comparing an arbitrary mid-travel voltage with these limits would manufacture a failure that the monitor does not describe.

What to preserve during diagnosis

Retain the closed-stop state, averaged feedback and any available learning status. Establish that the controller reached and recognized the required stop before interpreting the voltage comparison. The document does not state that a failed stop comparison proves a bent linkage, failed position sensor or a particular adjustment error.

Verification should repeat the applicable stop-reference evaluation under the prescribed service conditions. Do not force the actuator against a stop or manually adjust it using these summary figures. The exact application procedure is needed for commanded movement and any learning operation; this article only explains the controller's evidence.

Source and applicability

2025 GM 07A-2 documented monitor only; module and calibration applicability must be matched to the vehicle. The application-matrix filename join remains unresolved; no model or engine fitment is inferred. GM PDF, page 863.