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1999 MERCEDES-BENZ ML
3.2L V6•AWD•AUTOMATIC•gas
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Repairs0Labor504Torque2192Fluid8DTC1591Battery1Maintenance0Recalls0
P1400moderate severityPowertrain

EGR Output Stage Malfunction

on 1999 Mercedes-Benz ML 3.2L V6 · AWD

What this code means

The ECU detected a malfunction in the EGR (Exhaust Gas Recirculation) valve output stage. The ECU cannot properly command the EGR valve, affecting NOx emission control.

Symptoms

  • Check Engine Light
  • Higher NOx emissions
  • Failed emissions test
  • Possible rough idle
  • Slight power loss

Common causes

  • Faulty EGR valve actuator
  • Carbon buildup in EGR valve
  • Wiring fault to EGR valve
  • ECU EGR driver circuit failure
  • EGR valve stuck

Diagnostic steps

  1. Test EGR valve operation with scan tool command
  2. Inspect EGR valve for carbon buildup
  3. Test EGR valve solenoid resistance
  4. Check wiring and connector
  5. Monitor EGR position feedback

Repair notes

Clean or replace the EGR valve; repair wiring if damaged.

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