What it means
HVIL loop F voltage above expected range. A communication loss with this module breaks any function relying on its data — diagnostic tools may show 'no response' and dependent modules can fall into limp mode.
At a glance
- Usually lights the warning light of the system that lost communication
- The engine or gearbox may go into limp mode
How it works
The high-voltage interlock loop F monitors whether covered connectors and components in that part of the system are securely connected. The control module sets this code when loop F voltage is higher than expected, which can occur when the circuit is open.
Common causes
Most likely first.
- Interlock loop open
- Gateway module routing CAN messages incorrectly
- CAN terminating resistor (120 Ω) drifted out of spec
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
How to diagnose it
- Capture freeze-frame data and scan for related interlock or communication faults to see whether loop F is the only affected circuit.
- With the vehicle powered down as directed by the manufacturer, inspect accessible loop F connectors and wiring for a loose or disconnected connection, damage, or corrosion.
- Check scan-tool live interlock data, if available, to compare loop F with loops E and G and confirm the abnormal reading is localized.
- Have a qualified high-voltage technician check loop F continuity and connector engagement using the manufacturer's safety procedure and specifications.
- If the loop itself tests correctly, investigate gateway routing and CAN termination with vehicle-specific wiring information.
Common fixes
- Reconnect a loose loop F connector using the manufacturer's procedure.
- Repair damaged or corroded loop F wiring and terminals.
- Replace a confirmed faulty interlock component in loop F.
- Repair verified gateway or CAN termination faults after testing.
Can I keep driving?
Avoid driving if the vehicle displays high-voltage warnings, reduced power, or shutdown behavior, since propulsion or charging may be limited. Have the interlock inspected by a qualified high-voltage technician.
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.