U0120Lost Communication With Starter/Generator Control Module
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- 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.
- What you may notice
- MIL and hybrid or charging warning
- Start-stop or engine start by the electric machine unavailable
- Battery not charged while driving
- Likely causes
- LikelyFault on the CAN lines between hybrid controller and generator control unit
- PossibleStarter/generator control unit faulty (replacement if it stores U0120 itself)
- PossibleLow 12 V supply or poor ground at the power electronics
- RareReceiving hybrid controller faulty
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.