P2B65: An overspeed or dry-run classification is not direct proof of trapped air

P2B65 is listed in Ford’s auxiliary pump B section as an overspeed/dry-run control classification, paired with P261A_B1. The generic definition also refers to air in the system. That wording should not be expanded into a claim that a particular air pocket has been located or that the cooling circuit is certainly empty.

A reported operating state still needs verification

The pump monitoring group executes continuously, specifies five seconds and requires battery voltage of at least 11 V. The source does not disclose the overspeed boundary, dry-run detection formula or commanded-speed relationship used for this code.

Consequently, an rpm value borrowed from another pump cannot serve as the verification limit. The useful distinction is between the reported overspeed/dry-run category and the separate stuck, underspeed, supply or thermal classifications in the same family.

Confirm which pump the source refers to

The heading and P261A family indicate pump B, but the row’s text prints pump A. This unresolved mapping must be checked against the actual vehicle before selecting a cooling loop or service procedure.

Preserve the exact identifier, requested pump operation and available speed/status feedback. Those records can guide further diagnosis without assuming the underlying cause. The summary does not authorize running a pump dry, choosing a bleeding procedure or replacing a component solely from this classification.

Source and applicability

Ford 2024–2025 gasoline OBD summary, July 16, 2024 revision; only the described monitor and architecture. Model, engine and calibration fitment are not inferred. The monitor explanation does not identify a failed part or replace the applicable service procedure. Ford PDF, page 145.