What it means
HVIL loop G 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 G monitors the connection state of covered high-voltage components. The control module sets this code when loop G voltage rises above its expected range, a condition that can occur if the loop 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 check for related interlock and communication codes to see whether the issue is confined to loop G.
- With the vehicle safely powered down as directed by the manufacturer, inspect accessible loop G connectors and wiring for a loose or disconnected connection, damage, or corrosion.
- Compare live interlock status for loop G with neighboring loops, if supported by the scan tool, to check whether only G is abnormal.
- Have a qualified high-voltage technician test loop G continuity and connector seating using the manufacturer's procedures and specifications.
- If the loop tests correctly, investigate gateway routing and CAN termination using vehicle-specific wiring information.
Common fixes
- Reconnect a loose loop G connector according to the manufacturer's procedure.
- Repair damaged or corroded loop G wiring or terminals.
- Replace a loop G interlock component confirmed faulty by testing.
- Repair verified gateway routing or CAN termination faults.
Can I keep driving?
Avoid driving if high-voltage warnings, reduced power, or shutdown occur, as the vehicle may restrict propulsion or charging. Have the loop 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.