What it means
The ECM detects a circuit 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
The hybrid or EV battery management system uses voltage-sense circuit F to monitor a portion of the high-voltage battery pack. This code sets when the module detects an electrical circuit fault that makes the F reading unreliable, without identifying a specifically low, high, or erratic signal.
Common causes
Most likely first.
- Fault in the voltage-sensing circuit
- Damaged wiring or poor connector contact
- Voltage-sensing component fault
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 check related hybrid battery codes to see when the F circuit fault occurred and whether other sensing circuits are affected.
- With the vehicle powered down according to its manufacturer service procedure, visually inspect accessible F-circuit wiring and connectors for damage, corrosion, looseness, or signs of moisture.
- Use scan-tool data to compare the F voltage reading with other pack-sensing readings under the same conditions and look for an implausible or missing value.
- Have a qualified hybrid technician test F-circuit continuity and connections using the manufacturer's high-voltage safety procedures.
- If the wiring and connections pass, test the F voltage-sensing component and its module input against the manufacturer's diagnostic procedure.
Common fixes
- Clean and securely reconnect a loose or contaminated F-circuit connector.
- Repair damaged F-circuit wiring or connector terminals.
- Replace a confirmed faulty F voltage-sensing component.
- Repair or replace a module only if its F-circuit input is confirmed faulty.
Can I keep driving?
Avoid relying on electric power or attempting long trips while the hybrid warning or reduced-power condition is present; charging may also be limited. If power drops sharply or the vehicle displays a high-voltage system warning, stop somewhere safe 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.