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U0672 Lost Communication With Engine Coolant Pump

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

GM's 2.0 L LSY and 2.7 L L3B four-cylinders circulate coolant with an electric main pump that the engine controller commands over LIN. U0672 sets when the pump's response frame MWP_Rsp is missing for at least 250 ms (25OBDG03B; same logic in 19OBDG03D for the L3B) once the LIN channel is up, the relay is powered and battery voltage exceeds 11 V; as a Type A fault it turns the MIL on at once. GM bulletin PIP5863C covers 2019-2024 Silverado/Sierra 1500, Colorado/Canyon, Blazer, Acadia, Envision and Cadillac CT4 to XT6: check terminals and crimps, unplug and reconnect the pump, clear the code; if it stays away, release the car. U019F names a separate pump control module, U04A0 its invalid data. Watch engine temperature.

Likely causes

Poor terminal tension, crimp or lock at the electric pump connector
LIN, supply or ground wire to the pump chafed or contaminated
Pump electronics or motor failed
Pump relay or fuse supplying the pump faulty

Symptoms

  • Check engine light immediately
  • Rising coolant temperature or overheating warning
  • Weak cabin heating
  • Reduced engine power to protect the engine

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€40–900
Time0.3–3 h

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

Parts involved

engine coolant pumpvehicle bus wiring

Related codes

U019FU04A0U0623P26CAP26CBP2B85P2BA2

References: gsi.ext.gm.com, static.nhtsa.gov, gsi.ext.gm.com.