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2012 SUBARU IMPREZA
2.5L H4•AWD•CVT•gas•turbo
6 active safety recalls on this vehicle — view recalls
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Repairs0Labor503Torque3396Fluid9DTC1108Battery1Maintenance0Recalls6
C0521moderate severityChassis

AWD Coupling Overheating

on 2012 Subaru Impreza 2.5L H4 · AWD

What this code means

The AWD coupling unit has exceeded its maximum safe operating temperature.

Symptoms

  • AWD warning light
  • AWD disengaged automatically
  • Burning smell from rear differential area
  • Reduced traction warning

Common causes

  • Sustained AWD engagement during tire size mismatch
  • Mismatched tires causing continuous slip
  • Coupling fluid breakdown
  • Driving on dry pavement in locked 4WD mode

Diagnostic steps

  1. Check all tire sizes match within specification
  2. Inspect coupling fluid condition
  3. Verify correct tire rotation pattern followed
  4. Check coupling temperature sensor
  5. Inspect coupling for fluid leak

Repair notes

Allow coupling to cool. Verify tire sizes match. Replace coupling fluid. Correct tire mismatch.

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