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U044D Invalid Data Received From Generator B Control Module

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U044D names the generator B control module. Ford uses the A version for its LIN-controlled alternator: in SSM 50737, 2021-22 F-150 trucks with the 2.7L EcoBoost warn about the charging system and store U012D and U042E in the PCM because a LIN wire rubs through to ground close to the engine mount on the left. A B unit would then be the regulator of a second alternator, as found on trucks with dual generators; Ford's 2014 code list already contains circuit codes for generator 2. U044D is set when that regulator answers but its status, load or fault data are invalid; U012F is lost contact. No manufacturer documents U044D publicly. The engine computer then cannot steer the second alternator reliably, so charging capacity may drop and a battery or charging warning may appear.

Likely causes

Chafed or shorted LIN wire to the second alternator
Faulty voltage regulator of alternator B
Second alternator not configured correctly in the engine computer

Symptoms

  • Battery or charging system warning
  • Low charging voltage under high electrical load

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–700
Time0.5–2.5 h

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

Parts involved

generator module balternator

Related codes

U012FU042EU012D

References: static.nhtsa.gov, performanceparts.ford.com.