Powertrain, generic · Hybrid propulsion

P0B38 Motor Electronics Coolant Pump B Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Hybrid and electric drives cool the inverter and motor electronics with electric coolant pumps; J2012 numbers them A, B and C. P0B38 sets when the controller detects an open or general fault in the control line of pump B, typically by checking the driver output for missing load current. No manufacturer documents P0B38 publicly. FCA uses a pump B on the Jeep Compass and Renegade 4xe, where bulletins name its performance code P0C74, and Mercedes uses the pump A code P0A05 for an open control circuit of the low-temperature circuit pump on M264 engines. CARB requires output components of inverter thermal management to be monitored. Expect a coolant or hybrid warning and power reduction if electronics overheat.

Likely causes

Pump connector loose, corroded or terminal pushed out
Open control wire between controller and pump
Pump electronics or motor failed open
Driver stage in the controlling module faulty

Symptoms

  • Hybrid system or coolant warning, MIL on
  • Reduced electric drive power when electronics get hot
  • Pump not running audibly after switch-on

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–600
Time0.5–3 h

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

Parts involved

motor electronics coolant pump bwiring harnesshybrid control module

Related codes

P0B39P0B3AP0C74P0E50P0A05P2D05

References: law.cornell.edu, static.nhtsa.gov, static.nhtsa.gov.