Network, generic

U019F Lost Communication With Engine Coolant Pump Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

U019F means the electric engine coolant pump, which carries its own control electronics, has stopped answering. Mercedes documents it on two engines: on the M256 six-cylinder the engine controller stores U019F00 or U019F87 with a red coolant warning; LI20.10-P-075374 checks the 12 V and 48 V plugs of pump M75/11, its ground and fuse F153/2 and, if the pump touches the heat shield, insulates it or replaces the controller. On C350e and GLC350e hybrids the check engine lamp lights as well; MED40 software or a new pump fixes it. Ford SSM 46857 and 47790 (C-MAX, Fusion, MKZ hybrids) report it with an MIL from water in connectors such as C1651. Mazda warns that swapped pumps on the CX-90/CX-70 PHEV set it. U04A0 is invalid data.

Likely causes

Pump supply plug, 48 V connector or ground loose or dirty (Mercedes)
Water or corrosion in front-end connectors (Ford hybrids)
Similar-looking pumps swapped or wrong part ordered (Mazda PHEV)
Engine controller software outdated (Mercedes MED40)
Electric coolant pump electronics faulty

Symptoms

  • Red coolant temperature warning
  • MIL or check engine lamp on
  • Engine power reduced to protect against overheating

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€0–900
Time0.5–4 h

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

Parts involved

coolant pump modulecan bus

Related codes

P26CAP26CBP26D0U0284U04A0

References: static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov, static.nhtsa.gov.