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Home >> Mercury >> 2009 >> Sable Premier, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 1255 (Engine Controls - Powertrain DTC Charts & Descriptions (Except Diesel & Hybrid)) >> DTC Diagnosis >> DTC P0402: - Exhaust Gas RECIRCULATION (EGR) Flow Excessive Detected

DTC P0402: - Exhaust Gas RECIRCULATION (EGR) Flow Excessive Detected

WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2009 Mercury Mountaineer, 2009 Mercury Milan, 2009 Mercury Mariner, 2009 Mercury Grand Marquis, and 2009 Lincoln Town Car. However, it is still accessible from the selected car via links, so may be relevant.
DTC P0402: - EXHAUST GAS RECIRCULATION (EGR) FLOW EXCESSIVE DETECTED

Description:  The EGR system is monitored for undesired EGR flow during idle. The EGR monitor looks at the differential pressure feedback EGR (DPFE) signal at idle and compares it to the stored signal measured during ignition on engine off. The test does not pass when the signal at idle is greater than at ignition on engine off by a calibrated amount.
Possible Causes: 
  • EGR valve stuck open
  • Plugged EGR vacuum regulator solenoid vent
  • Plugged EGR tube
  • Slow responding differential pressure feedback EGR sensor
  • Damaged differential pressure feedback EGR sensor.
  • Incorrect vacuum hose connection
  • Plugged vacuum hoses
  • EVR circuit short to ground
  • Damaged EGR vacuum regulator solenoid
Diagnostic Aids:  A DPFEGR PID reading that is greater at idle than during KOEO by 0.5 volt or a rough engine idle may indicate a hard fault.
Application  Key On Engine Off  Key On Engine Running  Continuous Memory 
Crown Victoria,
E-Series,
Explorer 4.0L,
Explorer Sport
Trac 4.0L,
F-150 4.6L 2V,
F-Super Duty
6.8L,
Grand
Marquis,
Mountaineer
4.0L,
Mustang 4.0L,
Mustang 5.4L,
Town Car
- GO to Pinpoint Test HH . GO to Pinpoint Test HH .
All others - GO to Pinpoint Test HE . GO to Pinpoint Test HE .