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2012 MERCEDES-BENZ ML
3.5L V6•AWD•AUTOMATIC•gas•M272
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Repairs0Labor492Torque2165Fluid8DTC1852Battery2Maintenance0Recalls0
P1186high severityPowertrain

Fuel Pressure Monitoring Minimum Pressure Too Low

on 2012 Mercedes-Benz ML 3.5L V6 · AWD

What this code means

The ECU detected that the fuel rail pressure has fallen below the minimum required operating pressure. The high-pressure fuel system is not maintaining adequate pressure for proper injection.

Symptoms

  • Check Engine Light
  • Loss of power
  • Hard starting
  • Engine stalling
  • Rough idle

Common causes

  • Failing high-pressure fuel pump
  • Clogged fuel filter
  • Leaking fuel injector seals
  • Low-pressure supply pump weak
  • Fuel pressure regulator failure

Diagnostic steps

  1. Monitor fuel rail pressure with scan tool
  2. Test low-pressure fuel pump output
  3. Inspect fuel filter
  4. Check for fuel injector leaks
  5. Test high-pressure pump mechanical output

Repair notes

Replace the failing fuel system component causing low rail pressure.

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