U067CLost Communication With Fan 3
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Some engines need a third electric cooling fan, for instance for a charge-air or auxiliary radiator, and LIN lets each fan carry its own speed electronics. GM's 2025 diesel table 25OBDG04B uses U067C for cooling fan 3: the response frame CFM3_Rsp must be missing for at least 2,437.5 ms, the LIN channel enabled and battery voltage above 11 V; the code is Type B, so the MIL lights after two trips. While it is active GM suspends the fan 3 speed checks, P2CBB for running slower than modelled and P30F2/P30F3 for feedback out of range, the high limit being 4,000 rpm. On the engines of GM's 23OBDG07 and 24OBDG07 the same fan instead sets the GM-specific U112A on a third LIN line. Watch engine temperature under load.
- What you may notice
- Check engine light after two trips
- High coolant or charge-air temperature at low speed or when towing
- Fan 3 silent or running constantly
- Likely causes
- LikelyLIN wire to fan 3 chafed or open
- PossibleHigh-current supply, fuse or ground of fan 3 faulty
- PossibleFan 3 controller electronics failed
- RareFan connector corroded by road spray
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €60 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.