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2009 AUDI A3
2.0L TDI•FWD•AUTOMATIC•diesel•turbo
5 active safety recalls on this vehicle — view recalls
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Repairs0Labor549Torque3443Fluid6DTC731Battery1Maintenance0Recalls5
P3851high severityPowertrain

DPF Regeneration Incomplete - Multiple Attempts

on 2009 Audi A3 2.0L TDI · FWD

What this code means

The DPF has failed to complete a regeneration cycle after multiple attempts. Soot loading continues to increase.

Symptoms

  • DPF warning light
  • Reduced power
  • Forced limp mode
  • Excessive exhaust temperature warnings
  • Strong exhaust smell during regen attempts
  • Fuel dilution of engine oil

Common causes

  • Driving pattern prevents regen completion (short trips)
  • EGR system fault preventing proper temperature
  • Injector fault affecting post-injection for regen
  • DPF catalyst coating degraded
  • Exhaust temperature sensor error

Diagnostic steps

  1. Check DPF soot loading level
  2. Review regen history and completion rates
  3. Test exhaust temperatures during regen attempt
  4. Check EGR system operation
  5. Inspect fuel injectors for proper post-injection

Repair notes

Perform forced DPF regeneration with scan tool. If soot loading is critical, DPF cleaning service may be needed. Address root cause preventing regen completion.

Other Powertrain codes on this vehicle

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