P0AA9

Hybrid/EV Battery Voltage Isolation Sensor Circuit Low

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$56–278 (est.)

Symptoms

Check Engine light comes on
Hybrid system power reduction
Error message on display
The car may go into emergency mode
Possible battery charging problems

Causes

Damage to the insulation of high-voltage cables
Insulation sensor fault
Problems with the sensor wiring harness
Corrosion or poor contact in connectors
Malfunction of the high-voltage battery control module

How to Fix

Check the condition of high-voltage insulation
Diagnose the insulation sensor and its circuit
Check connections and connectors in the sensor circuit
Replace damaged components
Repair only from an authorized dealer

Related codes

P0AA6 P0AA7 P0AA8