2023 Chevrolet Bolt EUV

Chevy Bolt EUV P0AA6 HV Isolation — Chafed Wire at Battery Module Bracket

P0AA6 P0AA4 Published 2025-02-03 Updated 2025-02-03
Chevrolet Bolt EUV P0AA6 HV isolation chafed wire battery module bracket

2023 Chevy Bolt EUV presented with P0AA6 HV isolation fault with no apparent cause. Isolation resistance 9.4 kΩ on HV negative bus. Internal battery pack wire chafing against a module retention bracket — fault confirmed during pack disassembly.

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The Problem
2023 Chevrolet Bolt EUV Premier (34,600 miles) towed in with 'Propulsion Power Reduced' and P0AA6. No recent service, no water exposure, no damage. P0AA6 and P0AA4 stored in BMS.
Diagnostic Procedure
  1. 1. Confirm P0AA6. BMS reports HV negative isolation: 9.4 kΩ. Positive bus: >1 MΩ.
  2. 2. Segment negative bus externally: disconnect accessible negative HV points. No change in isolation after external disconnections — fault is internal to the battery pack.
  3. 3. De-energize HV system. Remove battery pack per Chevy service procedure (significant labor — set customer expectations).
  4. 4. With pack on bench, perform isolation check: negative bus still 9.4 kΩ. Fault confirmed internal to pack.
  5. 5. Partially disassemble pack access panels. Inspect inter-module wiring for chafe points.
  6. 6. At module 7 retention bracket: a cell sense wire (negative potential) has been pulled tight against a stamped bracket edge — insulation worn through over approximately 30,000 miles of vibration, exposing conductor against the bracket (chassis potential).
  7. 7. Repair: insulate exposed wire section with appropriate-rated heat shrink, add protective split loom, re-route with 15mm additional clearance from bracket edge. Secure with cable tie.
  8. 8. Pack isolation check: negative bus >1.5 MΩ. Reinstall pack. Clear codes. Vehicle enters Drive.
  9. 9. 20-mile test drive. P0AA6 does not return.
Resolution & Root Cause
Internal battery pack wire re-insulated and re-routed at bracket chafe point. Isolation restored, all codes cleared.
💡 Key Lesson
P0AA6 on Chevy Bolt EUV with no external cause (water, damage, service history) and fault isolated to inside the battery pack — the repair requires pack removal. On this generation, cell sense wire chafing against module retention brackets is a known failure mode from approximately 30,000 miles onward. The fix is a wire repair, not a pack replacement.
About This Case

This case was solved remotely by an HVDesk specialist with 15+ years of hands-on experience across major EV platforms including Tesla, Hyundai/Kia, Volkswagen ID series, BMW i-series, and Ford EVs. The procedure was provided as structured remote support to an independent auto repair shop.