What it means
The control module detects a range or performance 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 reports an electrical-isolation reading to the control module. This range/performance code sets when the circuit reading is present but does not behave within the expected range or response, rather than being identified simply as low or high.
Common causes
Most likely first.
- Isolation sensor circuit fault
- Wiring or connector fault
- Control module fault
Symptoms
- Hybrid system warning light
How to diagnose it
- Read hybrid-system codes and freeze-frame data to see when the isolation-sensor reading moved outside its expected behavior and whether related faults are present.
- Review live isolation-sensor data for implausible, drifting, or inconsistent readings under the manufacturer's prescribed conditions.
- With the vehicle safely powered down according to service information, inspect the sensor connector, accessible wiring, and grounds for corrosion, damage, or poor contact.
- Check the sensor circuit for shorts, opens, or unstable connections using the manufacturer's diagnostic procedure.
- Have a qualified hybrid technician test the isolation sensor's response against the manufacturer's specification, without probing high-voltage terminals.
- If the sensor and circuit pass, check module inputs and grounds as directed by the manufacturer.
Common fixes
- Repair a loose, corroded, or damaged sensor connector.
- Repair wiring or ground faults that cause an unstable or out-of-range sensor reading.
- Replace the isolation sensor if its response fails the manufacturer's tests.
- Repair or replace the control module only if its input or ground checks fail.
Can I keep driving?
Avoid demanding driving if the hybrid warning is accompanied by reduced or unavailable electric drive, since the system may further limit operation. Have the isolation-sensor range fault diagnosed before relying on the vehicle for longer trips.
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.