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U0648 Lost Communication With Motor Electronics Coolant Pump C

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

U0648 belongs to a third digitally controlled pump in the motor electronics cooling, labelled C, which only more elaborate layouts carry, for example a generator inverter with its own loop. The fault means the pump has dropped off the bus. No carmaker publishes a description of U0648, so which component pump C cools has to be taken from the vehicle's own service information. CARB's rule for inverter thermal management, (e)(15.2.3)(B)(ii), still applies to hybrids. A pump with plain wiring would report P2BD4 to P2BD7 or the internal faults P2D0A to P2D0E. If A, B and C drop out together, look for a shared cause such as a common fuse, ground point or bus master rather than three failed pumps.

Likely causes

Data or supply line to pump C damaged

Shared fuse or ground point of the pumps faulty (several pump codes at once)

Pump C controller failed

Symptoms

Hybrid or EV warning lamp
Reduced power from the electric machine cooled by pump C

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€60–700

Time0.5–2.5 h

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

Parts involved

motor electronics coolant pump cvehicle bus wiring

References: law.cornell.edu, bosch-mobility.com.