OBD-II Code
P0AA6
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$380–$7,200
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0AA6 indicates the BECM has detected an electrical isolation fault between the high-voltage battery pack (and its associated cabling, inverter, MG1/MG2) and the vehicle chassis — the isolation resistance has dropped below the safety threshold (typically 100 ohms per volt, so a 200V Prius pack requires 20K ohms minimum to chassis, a 360V Volt pack requires 36K ohms).
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0AA6 indicates the BECM has detected an electrical isolation fault between the high-voltage battery pack (and its associated cabling, inverter, MG1/…
P0AA6 indicates the BECM has detected an electrical isolation fault between the high-voltage battery pack (and its associated cabling, inverter, MG1/MG2) and the vehicle chassis — the isolation resistance has dropped below the safety threshold (typically 100 ohms per volt, so a 200V Prius pack requires 20K ohms minimum to chassis, a 360V Volt pack requires 36K ohms). This is a SAFETY code; the orange HV cables and the pack itself are now leaking current to the chassis at a level that could shock a technician.
Cheapest-first diagnostic ladder
- do NOT probe HV components without PPE and an insulation tester.
- Start with a visual inspection (12V system disconnected, service plug pulled, 10-minute capacitor discharge wait) of all orange HV cable connectors for moisture, green corrosion, or damaged insulation.
- Caveat: P0AA6 can be triggered by a wet 12V/HV junction box after a car wash or heavy rain, and will self-clear after the area dries — but if it returns, do not ignore it; coolant intrusion into the pack is a thermal-runaway risk on lithium platforms.
Vehicle-specific patterns2010-2015 Toyota Prius Gen 3 (ZVW30) — HV battery coolant intrusion from leaking inverter coolant hose dripping onto pack lid; Toyota TSB T-SB-0023-1…
- 2010-2015Toyota Prius Gen 3 (ZVW30) — HV battery coolant intrusion from leaking inverter coolant hose dripping onto pack lid; Toyota TSB T-SB-0023-15 inspects and reseals.
- 2011-2015Chevrolet Volt — coolant leak from the battery thermal management loop into the pack itself (lithium-ion T-pack) triggers P0AA6 with companion P1FFF; GM safety recall 15V-145 covered some VINs.
- 2005-2012Ford Escape Hybrid — HV cable insulation degradation at the inverter connector from underhood heat cycling.
- 2013-2018Ford Fusion Hybrid — HV junction box water intrusion from cowl drain blockage.
Estimated repair$380 to $7,200.
Look up another code
More free tools