MG ZS EV P0AA6: Insulation fault case after high-voltage battery water ingress and corrosion

MG ZS EV P0AA6: Insulation fault case after high-voltage battery water ingress and corrosion

Symptoms

• The vehicle would not start, charge or drive, and indicated high-voltage battery and EV system insulation faults. ^[1]

Diagnostic trouble codes

• P0AA6 (generic): EV system insulation fault (description in the original repairer's vehicle case) ^[1]

Possible causes

• The battery assembly in this vehicle lacked sealing, resulting in water ingress and internal corrosion; do not diagnose every P0AA6 as battery pack damage. ^[1]

Checks

• Have a qualified high-voltage technician locate the insulation fault in accordance with the manufacturer's safe isolation requirements, then inspect the battery assembly for sealing, water ingress and corrosion. The source does not disclose specific measurement thresholds. ^[1]

What to do

• In the original case, severe corrosion led to replacement with a tested reused battery pack, followed by safety checks, code clearing and functional verification after reassembly. The actual repair plan should determine repair or replacement based on the fault location and battery condition. ^[1]

Applicability and limits

• Only applies to the publicly available LKQ Electriq battery-electric MG ZS high-voltage battery water ingress case; the source names the model MG ZS. Its Affected Vehicles section lists 2021–2026, but the repaired vehicle's model year is not disclosed. This refers only to the ZS EV case and does not cover combustion-engine ZS or Hybrid+. No vehicle model has been linked. Scope: unknown ^[1]
• 2021–2026 as listed under Affected Vehicles in the source; this does not mean the case vehicle's model year is known
• The source abbreviates the name as MG ZS, while the content explicitly concerns a high-voltage battery and battery-electric drive
• Does not cover combustion-engine ZS or ZS Hybrid+
• Only applies to the repair case involving water ingress, missing sealing and severe corrosion

Related part categories

• Traction battery / High-voltage traction battery assembly / High-voltage battery ^[1]

Sources

[Source 1] LKQ Electriq: MG ZS (2021–2026) Won’t Start – High Voltage Battery Water Ingress & Isolation Fault — The following fault code(s) may be present; Affected Vehicles; MG ZS Diagnostic Report; Parts Repaired or Replaced; MG ZS Repairs/Resolution (accessed 2026-11-01)
https://lkqelectriq.co.uk/project/mg-zs-2021-wont-start-high-voltage-battery/