P0BC0: Hybrid/EV Battery Pack Cooling Fan Supply Voltage Circuit Low
What to do
As P0BBF — and note a slow fan is more insidious than a dead one, because the car may not notice. The measurement that matters is taken at the fan while it runs.
What this code means
The cooling fan's supply is present but sagging below what it should be.
A fan on low voltage does not stop — it runs slowly, which is worse than stopping in one specific way: the module may believe the fan is working while the pack is not actually being cooled. The usual causes are resistance in the feed rather than failure at either end. Measure at the fan while it is running, not at the fuse. The family's argument is at P0BBF.
Likely causes
Start here
- Corroded or loose connector · easy
Less common
- Low system voltage · moderate
- Damaged wiring harness · moderate
- Faulty hybrid battery cooling fan · 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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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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