What it means
The ECM detects a high fault on the hybrid/ev battery pack voltage sense f circuit. Reading cannot be used reliably for control.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
Voltage-sense circuit F monitors a portion of the hybrid or EV battery pack. This code sets when the module sees the F signal above its expected electrical range, often because the signal is shorted toward a voltage source, making the reading unreliable for battery control.
Common causes
Most likely first.
- Signal circuit short to voltage
- Faulty voltage-sensing component
- Damaged wiring or poor connector contact
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
- Record freeze-frame data and related codes to establish when circuit F went high and whether other sensing circuits show a similar fault.
- Compare live F-circuit data with the other pack-sensing readings to verify that the F signal is abnormally high.
- With the vehicle powered down by the manufacturer's procedure, inspect accessible F-circuit wiring for shorts, damaged insulation, and connectors for corrosion or poor seating.
- Have a qualified hybrid technician test the F signal circuit for a short to voltage and verify its connections under the manufacturer's safety procedure.
- If no wiring short is found, test the F voltage-sensing component and module input against the manufacturer's diagnostic procedure.
Common fixes
- Clean and securely reconnect a poor-contact F-circuit connector.
- Repair F-circuit wiring shorted to a voltage source or with damaged insulation.
- Replace a confirmed faulty F voltage-sensing component.
- Repair or replace the module only if testing confirms its F input is faulty.
Can I keep driving?
Keep driving to a minimum because the battery system may limit power or charging when it cannot trust the F reading. If a high-voltage warning appears or the vehicle loses power, stop safely and arrange qualified hybrid service.
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.