What it means
The control module detects a fault in the hybrid battery voltage isolation sensor circuit.
At a glance
- Usually lights the check-engine light
- The engine or gearbox may go into limp mode
How it works
The hybrid battery voltage isolation sensor circuit carries information used to monitor electrical isolation between the high-voltage battery system and the vehicle chassis. The control module checks this circuit for a general electrical fault; this code does not specify whether the signal is low, high, or intermittent.
Common causes
Most likely first.
- Sensor circuit wiring or connector fault
- Isolation sensor fault
- Control module fault
Symptoms
- Hybrid system warning light
How to diagnose it
- Read all hybrid-system codes and freeze-frame data to see whether other isolation, battery, or sensor-circuit faults occurred at the same time.
- Check scan-tool data for the isolation-sensor reading and any related hybrid-system status or warning.
- With the vehicle safely powered down as the manufacturer directs, inspect accessible sensor connectors, low-voltage wiring, and grounds for looseness, corrosion, or damage.
- Check the isolation sensor circuit wiring for continuity, shorts, and poor connections using the manufacturer's procedure.
- Have a qualified hybrid technician assess the isolation sensor against the manufacturer's specification without probing high-voltage terminals.
- If the sensor circuit and sensor pass, follow the specified checks for the controlling module and its grounds.
Common fixes
- Secure or clean a loose or corroded isolation-sensor connector.
- Repair damaged wiring or a poor ground in the isolation sensor circuit.
- Replace the isolation sensor if it fails the manufacturer's tests.
- Repair or replace the control module only if it fails the specified circuit checks.
Can I keep driving?
Treat a hybrid-system warning involving battery isolation as a reason to avoid unnecessary driving, especially if the vehicle limits or disables hybrid operation. Do not touch high-voltage components; have a qualified hybrid technician assess it.
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.