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U0699 Lost Communication With Coolant Pump F

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Pump F is the sixth auxiliary electric coolant pump in the generic lettering, and the code flags that this pump has stopped responding on its data line. No manufacturer documents U0699 publicly; even the Mercedes bulletin that uses the E code for a low-temperature pump lists no F. Six separately addressed pumps point to elaborate thermal systems, for example vehicles with several cooling loops for engine, charge air, electronics and cabin. Such pumps typically take a PWM or LIN speed command and report their own condition, as Bosch describes for the PDE, and LIN is widely used for small motor nodes of this kind. CARB asks for an approved monitoring plan when an electric pump rather than a thermostat regulates engine temperature. P2D27 covers pump F's control performance.

Likely causes

Data, supply or ground wire to pump F damaged
Pump F electronics or motor failed
Controlling module or software fault

Symptoms

  • Warning light depending on manufacturer
  • Loop served by pump F runs too warm
  • Radiator fan running more often or at full speed

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–700
Time0.5–3 h

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

Parts involved

coolant pump fvehicle bus wiring

Related codes

U0698U0623U0624U062FU0649P2D27

References: law.cornell.edu, bosch-mobility.com, en.wikipedia.org.