U0647Lost Communication With Motor Electronics Coolant Pump B
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Cars fitted with two or more drive units, or with separate loops for the motor and its inverter, may fit a second networked pump in the motor electronics circuit, called B. U0647 is logged when this pump no longer returns its status frames. Public manufacturer documentation for U0647 does not exist. Since it is a separate node, the typical clue is that pump A and the rest of the bus still communicate, which narrows the search to pump B's own branch of wiring, its connector and its fuse. The conventional circuit codes for this pump are P0B38 to P0B3A, with P0C74 for performance and P2D05 to P2D09 for internal pump faults. Electric pumps such as Bosch's PCE generation take LIN commands and diagnose themselves. Expect reduced power from the axle that pump B cools.
- What you may notice
- Hybrid or EV warning lamp, MIL on hybrids
- Power limited on one drive unit
- Likely causes
- LikelyWiring branch or fuse that serves only pump B open
- PossiblePump B connector corroded or not fully seated
- PossiblePump B electronics failed
- 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 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.