Network, generic

U0120 Lost Communication With Starter/Generator Control Module

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

U0120 means the starter/generator control module, which drives an electric machine that can both crank the engine and produce electrical power, has dropped off the bus. Mitsubishi documents it for the Outlander PHEV (2018 and 2022): the hybrid controller (PHEV-ECU) sets U0120 when, after its supply has been within 10–16 V for more than 5 s, no frames from the generator control unit (GCU) housed within the power drive unit arrive for 0.3 s; confirmation uses the second of Mitsubishi’s OBD-II drive patterns, and whether the GCU itself has stored U0120 decides between replacing the GCU or the PHEV-ECU. Ford's 2014 powertrain code list also contains U0120. On 48 V mild hybrids with a belt or integrated starter generator it applies likewise. Expect lost start-stop or hybrid functions, a charging warning and the MIL.

Likely causes

Fault on the CAN lines between hybrid controller and generator control unit
Starter/generator control unit faulty (replacement if it stores U0120 itself)
Low 12 V supply or poor ground at the power electronics
Receiving hybrid controller faulty

Symptoms

  • MIL and hybrid or charging warning
  • Start-stop or engine start by the electric machine unavailable
  • Battery not charged while driving

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time1–5 h

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

Parts involved

starter generator modulecan bus wiring

Related codes

U0469P0A1EU0293U0111

References: mitsubishitechinfo.com, mitsubishitechinfo.com, performanceparts.ford.com, en.wikipedia.org.