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U04A0 Invalid Data Received From Engine Coolant Pump Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Engines with an electric main coolant pump carry a pump whose built-in electronics set the speed on request and send back status and fault information. Rheinmetall, for example, builds such pumps for main engine cooling with a LIN interface and extensive self-diagnosis, and Hella notes that electric pumps can stay off after a cold start so the engine warms faster. U04A0 means the engine controller still receives pump messages but finds speed, status or check values implausible. No manufacturer documents this code publicly. It matters for emissions because CARB 1968.2 expects coolant temperature to reach its closed-loop threshold in time, which depends on a correctly controlled pump. U019F and U0672 stand for lost contact. Watch the temperature gauge: the engine may run hot, limit power or keep the fan on.

Likely causes

Pump electronics faulty, often after overheating or coolant ingress
LIN or CAN wire or connector at the pump corroded or loose
Pump running dry or blocked (air in system, debris), reported as error state
Pump or engine controller software not matched after replacement

Symptoms

  • Check engine or coolant temperature warning
  • Engine runs hot or the cooling fan runs continuously
  • Reduced engine power to protect the engine

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€80–900
Time0.5–3 h

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

Parts involved

engine coolant pump module

Related codes

U019FU0672

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