U0632Lost Communication With Fan 1
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Many radiator fans now contain their own speed controller and take commands over LIN instead of relays. U0632 is set when fan 1 stops responding. GM (25OBDG03A, 25OBDG04B) fails it as Type B after 2.5 s without the fan's response frame and then suspends the fan speed checks P0494 and P30EE; the 2023/24 tables 23OBDG07 and 24OBDG07 allow three missed frames. Mitsubishi's 2023 Outlander PHEV assigns fan 1 to the right-hand radiator fan on LIN2 and sets the code after 2 s of failed communication. Mercedes bulletin LI20.00-P-076708 (GLC 254, GLE 167) reports the fan at full speed with a coolant warning and blames drivetrain controller software or LIN wiring; Audi bulletins for the Q7 cite chafed fan harnesses. Fans usually default to full speed.
- What you may notice
- Fan running continuously at full speed, loud
- Check engine light and coolant warning message
- On some Audi models limited engine speed or drive system fault message
- Likely causes
- LikelyFan harness chafed or pinched near the radiator or plenum (Audi bulletins)
- PossibleFan power feed (fusible link) or ground open
- PossibleOutdated software in the controller that runs the LIN bus (Mercedes PTCU)
- PossibleElectronics in fan 1 failed (replaced as fan assembly)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Often possible to do yourself.Typical cost: €50 – €1,200
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.