Powertrain, generic (extended)

P277C Electric/Auxiliary Transmission Fluid Pump B Motor Stalled

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P277C means the motor of auxiliary pump B is commanded to turn but stands still or nearly so. Volvo uses it: its technical journal 36774 covers 2024–2027 mild-hybrid S60, S90, V60/V90 Cross Country, XC40, XC60 and XC90 models with the Aisin TG-81SC eight-speed, where the TCM stores P277C07. If the code shows up only intermittently, no warning appears and stop-start still works, Volvo says to clear it and not to replace anything. Confirmed with a warning and dead stop-start, gearboxes built before serial 25M8L30144 are replaced, while later units go to engineering support first. Ford's pump A equivalent is P0C2A, which its 2024 summary links to a pump that may have lost prime. A jammed impeller or seized bearing is the classic cause.

Likely causes

Jammed impeller or seized pump bearing
Known hardware issue in early gearboxes (Volvo TG-81SC before the serial break)
Pump lost prime because of low fluid
One-off detection without a real fault

Symptoms

  • Transmission warning message in the cluster
  • Stop-start not working
  • Shifts too early, too late or erratic

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€0–6,000
Time0–12 h

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

Parts involved

aux trans pump bpump motor

Related codes

P0C2AP276FP276EP277AP277D

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