What it means
HVIL loop P 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 HVIL checks that high-voltage connectors and covers are safely engaged. The module monitors loop P voltage; this code sets when its signal falls below the expected range, which may result from a short to ground in that loop.
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
- Capture freeze-frame data and scan all modules for loop P, other HVIL, and communication codes to identify related faults.
- Check loop P live voltage or status against the manufacturer's specification and note whether the low reading is current or intermittent.
- With the high-voltage system safely disabled using the prescribed procedure, inspect accessible loop P wiring for crushed insulation, contact with ground, moisture, or corrosion.
- Have a qualified technician isolate loop P and test for a short to ground and verify circuit continuity following the manufacturer's procedure.
- If loop P passes circuit tests, investigate gateway routing or CAN termination only when related network evidence remains.
Common fixes
- Repair loop P wiring that is shorted to ground.
- Clean, secure, or replace a damaged loop P connector.
- Repair chafed wiring or corroded terminals in the loop P circuit.
- Correct a gateway or CAN termination fault only if network diagnosis confirms it.
Can I keep driving?
Avoid driving with a high-voltage warning, limp mode, or shutdown because the low loop P signal may cause high-voltage functions to be restricted or disabled. Do not handle the high-voltage circuit; have it checked by a qualified 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.