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U042E Invalid Data Received From Generator A Control Module

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

U042E points to the regulator of generator A, on many Ford models a smart alternator that the PCM commands over a LIN line and that answers with load, temperature and fault status. The PCM stores U042E when those answers come back distorted or implausible; if they stop altogether, U012D is set instead, and U0284 often joins because grille shutters may share the line. Ford's 2014 code list names the module generator control module and gives no MIL flag. Ford bulletins trace the trio of U012D, U0284 and U042E to wiring: water in connector C1050 on the 2022 Maverick 2.0 L, where the MIL comes from oxygen sensor codes P0036 and P0138 instead (SSM 50973), and LIN wire VE181 chafing to ground at a bracket of the left engine mount on the 2021-2022 F-150 2.7 L (SSM 50737). Expect a charging warning and a draining battery. U044D is generator B.

Likely causes

Chafed or shorted LIN wire between PCM and generator
Water intrusion or corrosion in a connector of the LIN circuit
Faulty voltage regulator of the generator

Symptoms

  • Check charging system message or battery lamp
  • Battery runs down, starting problems
  • Grille shutter codes stored at the same time

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€50–700
Time0.5–3 h

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

Parts involved

generator module a

Related codes

U012DU0284U044DU012F

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