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2001 AUDI A8
4.2L V8•AWD•AUTOMATIC•gas
2 active safety recalls on this vehicle — view recalls
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Repairs0Labor487Torque3149Fluid9DTC900Battery1Maintenance0Recalls2
P1602high severityPowertrain

Power Supply Voltage Too Low

on 2001 Audi A8 4.2L V8 · AWD

What this code means

The ECU detected that its supply voltage has dropped below the minimum operating threshold. Low voltage can cause erratic ECU behavior, false fault codes, and poor engine performance.

Symptoms

  • Check Engine Light
  • Multiple fault codes stored
  • Engine running rough
  • Starting difficulties
  • Electrical accessories dimming

Common causes

  • Weak or failing battery
  • Faulty alternator or voltage regulator
  • Corroded battery terminals
  • High-resistance connection in power supply
  • Parasitic drain depleting battery

Diagnostic steps

  1. Test battery voltage and load test
  2. Test alternator output voltage and current
  3. Inspect battery terminals and connections
  4. Check main power supply wiring to ECU
  5. Test for parasitic electrical drain

Repair notes

Replace the battery or alternator; clean and tighten all power supply connections.

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🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years. Spot an error? Use the Help link above — a human reads every report.
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