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2012 MERCEDES-BENZ ML
3.5L V6•AWD•AUTOMATIC•gas•M272
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Repairs0Labor492Torque2165Fluid8DTC1852Battery2Maintenance0Recalls0
P1642high severityPowertrain

ECM Incorrect Coding MT/AT Mismatch

on 2012 Mercedes-Benz ML 3.5L V6 · AWD

What this code means

The ECU detected that the transmission type coding (manual vs automatic) does not match the actual transmission installed. This causes incorrect shift strategy, torque management, and idle speed parameters.

Symptoms

  • Check Engine Light
  • Incorrect idle speed
  • Transmission control issues
  • Torque reduction malfunction
  • Starting difficulties

Common causes

  • ECU replaced without proper coding
  • Incorrect ECU installed
  • Coding data corrupted during update
  • Transmission swapped without ECU recoding

Diagnostic steps

  1. Read ECU coding for transmission type
  2. Compare coding to actual transmission installed
  3. Verify ECU part number matches vehicle
  4. Check for failed software updates
  5. Recode ECU with correct transmission type

Repair notes

Recode the ECU to match the installed transmission type using Mercedes Star Diagnosis.

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