Powertrain, generic (extended)

P2B65 Coolant Pump B Overspeed/Air in System

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

When a coolant pump draws in air, its impeller loses load: speed climbs and current drops. P2B65 reports this for coolant pump B. Ford's 2024 gasoline OBD summary lists it as failure type B1 (overspeed/dry run) of pump B under P261A. Bentley stores P2B6500, labelled air in system and static, in both engine control units 0001 and 0011 of the W12 Continental GT, GTC and Flying Spur from model years 2018 to 2024, often together with P2B8600 for pump A and a coolant warning in the instrument panel. Bentley's bulletin 2066669 (revisions 1 to 4, latest November 2025) starts with a pressure test and then checks vent hose 975 122 447H, whose built-in check valve can restrict flow; after replacement the circuit is bled. Pump D has P2B6C.

Likely causes

Air left in the circuit after filling or repair
Coolant loss through a leak, level too low
Restricting check valve in the vent hose (Bentley W12, 975 122 447H)
Speed or current detection inside the pump faulty

Symptoms

  • Coolant or overheating warning in the instrument cluster
  • Falling coolant level in the expansion tank
  • Gurgling noise or fluctuating temperature display

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–600
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

coolant pump bwiring harnessecm

Related codes

P2B86P2B63P2B64P2B6CP261B

References: fordservicecontent.com, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.