U063D code meaning
Lost Communication With Hybrid/EV Electronics Coolant Pump A
Network system Generic code U06xx codes Check engine light
What U063D means
The first electric pump of the power electronics loop, A, circulates coolant through the inverter, DC/DC converter and similar parts. Pumps of this class, such as Bosch's PAD2, take their speed command via PWM or LIN and run their own diagnosis; with LIN the controller also expects regular status replies. U063D is set when pump A stops answering. No manufacturer documents U063D publicly. California's OBD II regulation covers the outputs of inverter cooling too, which makes a lit MIL likely on hybrids. If the pump is dead rather than just mute, P2C68 (stalled) or P0CEA (performance) tend to follow. Pumps B and C report the same fault as U02BA and U02C1. The electronics heat up and the system cuts power.
U063D at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U063D
- Hybrid system warning and MIL
- Reduced electric drive power or engine kept running on hybrids
- Inverter or electronics overtemperature messages
Common causes of U063D
- Most likelyBlown fuse or open supply/ground to electronics coolant pump A
- PossibleLIN wire to the pump open, shorted or chafed
- PossiblePump electronics failed, often after running dry or overheating
- Less likelyFault in the hybrid or thermal controller acting as bus master
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Hv electronics coolant pump aVehicle bus wiring
What each part of U063D means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 3D | The exact fault in that area. |
What to do next
- Note U063D and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U063D
What does U063D mean?
U063D means "Lost Communication With Hybrid/EV Electronics Coolant Pump A". The first electric pump of the power electronics loop, A, circulates coolant through the inverter, DC/DC converter and similar parts. It is a generic code, so it means the same on every make.
Is it safe to drive with U063D?
Drive gently and only to a workshop. With U063D the car can go into limp mode (reduced power) to protect itself.
Will U063D fail an emissions test?
Yes, it can. U063D is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U063D to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will U063D clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.