P0B3A: Motor Electronics Coolant Pump B Control Circuit High
What to do
As P0B38 — the pump is not running, so expect the car to hold back on power or charging rate to protect components it cannot cool.
What this code means
The control circuit for the second electronics coolant pump is reading high — a short to a live circuit, or an open the module sees as an undriven output.
In practice this behaves like the open case at P0B38: the pump does not run, the loop it serves is not circulated, and the vehicle protects the electronics by limiting what it asks of them. The second-loop argument and the slow-charging symptom are there.
Likely causes
Start here
- Wiring shorted to voltage · moderate
- Faulty inverter coolant pump · moderate
Less common
- Corroded or loose connector · easy
- Open circuit in pump wiring · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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