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2020 AUDI R8
5.2L V10 (Gen 2, 562hp)•AWD•DCT•gas•DJPB
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Repairs0Labor479Torque2135Fluid10DTC1145Battery1Maintenance0Recalls0
P3801moderate severityPowertrain

48V Battery State of Charge Low

on 2020 Audi R8 5.2L V10 (Gen 2, 562hp) · AWD

What this code means

The 48V lithium-ion battery state of charge has dropped below the minimum threshold for mild hybrid functions.

Symptoms

  • Mild hybrid boost disabled
  • Start-stop disabled
  • Increased engine load
  • Regenerative braking not occurring
  • 48V battery warning
  • Higher fuel consumption

Common causes

  • 48V battery degradation
  • DC-DC converter not charging 48V battery
  • Excessive 48V electrical loads
  • 48V battery cell imbalance
  • Extended vehicle storage without charging

Diagnostic steps

  1. Read 48V battery SOC and voltage
  2. Check 48V DC-DC converter output
  3. Monitor 48V charging during deceleration
  4. Test 48V battery health
  5. Check for excessive 48V parasitic draw

Repair notes

Allow vehicle to run and recharge 48V battery. If SOC does not recover, test 48V battery and DC-DC converter. Replace if degraded.

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