What it means
The HV battery pack cooling fan 1 sense circuit reports a sense circuit high fault. Fan speed feedback is unreliable.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid battery cooling fan circulates air through the high-voltage battery pack, and its sense circuit reports fan 1 speed to the control module. P0BCA sets when the feedback signal is higher than expected, which can be caused by a signal wire shorted to B+, an open tachometer, or poor connector contact.
Common causes
Most likely first.
- Sense wire shorted to B+
- Open tachometer
- Connector pins corroded - high contact resistance
Symptoms
- EV/hybrid system warning light on
- Reduced power output or limp mode
- Charging may fail or be slowed
- Reduced electric range
How to diagnose it
- Save freeze-frame data and compare commanded fan 1 operation with live speed feedback, if available, to check whether the high signal persists regardless of fan command.
- With the vehicle powered down as directed by service information, inspect the fan 1 connector and harness for corrosion, loose pins, or damaged insulation that could connect the sense wire to B+.
- Check that the fan 1 connector terminals are seated and clean, since poor contact can disrupt feedback.
- Using the manufacturer's wiring information, test the fan 1 sense circuit for a short to B+ and check continuity through the circuit.
- If the wiring and connector pass, test the tachometer circuit and fan assembly against the manufacturer's specification for an open or failed tachometer.
Common fixes
- Clean and properly seat corroded or loose fan 1 sense terminals.
- Repair the sense wire shorted to B+ or its damaged harness section.
- Replace the fan assembly if its tachometer is open or fails the specified test.
- Clear the code and confirm feedback follows fan 1 operation.
Can I keep driving?
Limit driving and charging if the hybrid warning is present or power is reduced, and avoid conditions that add heat to the battery. A falsely high speed signal can cause protective limits, while an open tachometer may leave fan operation unverified.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.