2022 BMW i4

BMW i4 12V System Fault P0562 — Comfort Access Module Not Entering Sleep Mode

P0562 A0BC00 Published 2025-02-18 Updated 2025-02-18
BMW i4 P0562 12V drain parasitic draw comfort access CAS sleep mode

2022 BMW i4 eDrive40 with recurring '12V Battery Low' warnings and occasional no-start. P0562 stored. Standard parasitic draw test normal. Root cause: Comfort Access System (CAS) module not entering sleep mode due to a software bug, drawing 380mA continuously.

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The Problem
2022 BMW i4 eDrive40 (31,700 miles) presented with recurring '12V Battery Low' warnings, particularly after the car sat for 48+ hours. Battery load-tested good. P0562 (System Voltage Low) stored. No aftermarket accessories. Previous shop replaced 12V battery — problem returned in 3 weeks.
Diagnostic Procedure
  1. 1. Confirm P0562. 12V battery at 12.1V after 60-hour park — significantly discharged.
  2. 2. Standard parasitic draw test (measured 5 minutes after lock): 42mA — within BMW's 80mA spec.
  3. 3. Extended monitoring via current clamp data logger over 90 minutes post-lock. Draw drops to 42mA, then at 52 minutes: jumps to 380mA and stays there.
  4. 4. Identify active module at 52-minute mark. Using ISTA with active diagnostics, identify CAS (Comfort Access System) module still awake. All other modules sleeping.
  5. 5. CAS is polling for key fob proximity continuously — software bug in CAS firmware version 3.22.1 prevents sleep trigger after specific conditions (occurs when key fob is inside vehicle during lock, then removed after lock confirmation).
  6. 6. Check BMW Technical Information for known issue: TIS document SI-65 01 22 documents CAS sleep fault in firmware 3.22.1, recommends update to 3.24.0.
  7. 7. Update CAS firmware via ISTA to 3.24.0.
  8. 8. Post-update: CAS enters sleep at 18 minutes post-lock. Overnight current draw: 31mA. No 12V depletion after 5-day monitoring.
Resolution & Root Cause
CAS module firmware updated from 3.22.1 to 3.24.0 per BMW TIS SI-65 01 22. Sleep mode restored, parasitic draw normalized.
💡 Key Lesson
BMW i4 recurring 12V drain with a normal static parasitic draw test — log the current over 60-90 minutes, not just at 5 minutes. The CAS firmware bug in version 3.22.1 only keeps the module awake after a specific key-inside-lock sequence, which is why it's intermittent. Always check BMW TIS for CAS firmware bulletins before replacing batteries.
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.