What it means
HVIL loop G voltage below 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 checks continuity through monitored high-voltage connectors and components. This code sets when the control module reads loop G voltage below its expected range, suggesting a low signal such as one caused by a short to ground.
Common causes
Most likely first.
- Interlock wire shorted to ground
- 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
- Save freeze-frame data and check for other interlock, low-voltage, or communication codes that could point to a shared cause.
- With the vehicle powered down as specified by the manufacturer, inspect accessible loop G wiring for pinched or abraded insulation that could contact ground.
- Compare live data for loop G against other interlock loops, if available, to confirm the low reading is localized to G.
- Have a qualified high-voltage technician test loop G for a short to ground and check its connectors and interlock components against manufacturer specifications.
- If circuit checks pass, assess gateway routing and CAN termination using the vehicle wiring information.
Common fixes
- Repair loop G wiring with a confirmed short to ground or damaged insulation.
- Clean or repair corroded loop G connector terminals.
- Replace a failed loop G interlock component after confirming it by testing.
- Correct a verified gateway routing or CAN termination fault.
Can I keep driving?
Do not drive if high-voltage warnings, reduced power, or shutdown behavior occur; the vehicle may disable propulsion or charging. Have a qualified high-voltage technician inspect the system.
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.