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1997 AUDI A6
2.8L V6•AWD•AUTOMATIC•gas
2 active safety recalls on this vehicle — view recalls
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Repairs0Labor499Torque2194Fluid9DTC859Battery1Maintenance0Recalls2
P0172high severityPowertrain

System Too Rich Bank 1

on 1997 Audi A6 2.8L V6 · AWD

What this code means

The long-term fuel trim for Bank 1 has exceeded the negative limit, indicating the engine is running rich. The PCM is subtracting fuel to compensate.

Symptoms

  • Check Engine Light
  • Black exhaust smoke
  • Poor fuel economy
  • Rough idle
  • Fuel smell
  • Fouled spark plugs

Common causes

  • Leaking fuel injector
  • High fuel pressure
  • Faulty O2 sensor reading lean
  • Stuck-open EVAP purge valve
  • Saturated charcoal canister
  • Faulty MAF sensor (underreporting)

Diagnostic steps

  1. Check fuel trim values
  2. Test fuel pressure
  3. Check for leaking injectors (fuel pressure drop test)
  4. Inspect EVAP purge valve
  5. Test MAF sensor
  6. Inspect spark plugs

Repair notes

Check fuel injectors for leaks. Test fuel pressure regulator. Inspect EVAP system.

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