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2010 AUDI A3
2.0L TDI I4•FWD•AUTOMATIC•diesel•CBEA•turbo
5 active safety recalls on this vehicle — view recalls
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Repairs0Labor506Torque4360Fluid7DTC988Battery1Maintenance0Recalls5
U0100critical severityNetwork

Lost Communication with ECM/PCM

on 2010 Audi A3 2.0L TDI I4 · FWD

What this code means

The diagnostic system cannot communicate with the Engine Control Module.

Symptoms

  • Multiple warning lights
  • Engine may not start
  • Many systems inoperative
  • Cannot read engine codes

Common causes

  • PCM power or ground failure
  • CAN bus wiring issue
  • PCM failure
  • Fuse blown
  • Wiring harness damage

Diagnostic steps

  1. Check PCM fuses
  2. Test PCM power and ground circuits
  3. Check CAN bus wiring to PCM
  4. Try communicating with other modules
  5. Inspect wiring harness

Repair notes

Check fuses and power supply to PCM first. CAN bus issue is second most common.

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