U0646Lost Communication With Motor Electronics Coolant Pump A
- Generic OBD-II code · Network
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- In these titles, motor electronics stands for the power electronics that feed an electric drive motor in a hybrid or EV, and coolant pump A is the main electric pump of that loop. When it is commanded by LIN rather than a plain PWM wire, the controlling module can tell when the pump stops talking, which is what U0646 stores. No manufacturer documents U0646 publicly; the same pump with conventional wiring would instead set P0A05 to P0A07 for its control circuit or P0C73 for poor performance. Pumps that cool an inverter count as monitored thermal management outputs in CARB's rules, which argues for a MIL. Without confirmed flow the controller limits motor torque to protect the electronics, so the car may feel down on power.
- What you may notice
- Hybrid or EV system warning and MIL
- Limited drive motor torque or power
- Motor electronics over-temperature message, see P0A7C
- Likely causes
- LikelyFuse, relay or power feed of motor electronics pump A interrupted
- PossibleLIN line between controller and pump damaged
- PossibleIntegrated pump controller 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.