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Exhaust Gas Recirculation System Monitor - Differential Pressure Feedback EGR

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Differential Pressure Feedback EGR (DPFE) system monitor is an on-board strategy designed to test integrity and flow characteristics of EGR system. The monitor is activated during EGR system operation and after certain base engine conditions are satisfied. Input from ECT, CHT, IAT, TP and CKP sensors is required to activate EGR system monitor. Once activated, EGR system monitor will perform each test listed during engine modes and conditions indicated. Some EGR system monitor tests are also performed during KOEO or KOER self-test:

  1. DPFE sensor and circuit are continuously tested for opens and shorts. The monitor looks for DPFE circuit voltage to exceed maximum or minimum allowable limits. DTCs associated with this test are DTCs P1400 and P1401.
  2. EGR vacuum regulator solenoid is continuously tested for opens and shorts. The monitor looks for an EGR Vacuum Regulator (EGRVR) circuit voltage that is inconsistent with EGRVR circuit commanded output state. DTC associated with this test is DTC P1409.
  3. Test for a stuck open EGR valve or EGR flow at idle is continuously performed whenever at idle (TP sensor indicating closed throttle). The monitor compares DPFE circuit voltage at idle to DPFE circuit voltage stored during KOEO self-test to determine if EGR flow is present at idle. DTC associated with this test is DTC P0402.
  4. DPFE sensor upstream hose is tested once per drive cycle for disconnect and plugging. The test is performed with EGR valve closed and during a period of acceleration. PCM will momentarily command EGR valve closed. The monitor looks for DPFE sensor voltage to be inconsistent for a no flow voltage. A voltage increase or decrease during acceleration while EGR valve is closed may indicate a fault with signal hose during this test. DTC associated with this test is DTC P1405.
  5. EGR flow rate test is performed during a steady state when engine speed and load are moderate and EGR vacuum regulator duty cycle is high. The monitor compares DPFE circuit voltage to a desired EGR flow voltage for that state to determine if EGR flow rate is acceptable or insufficient. This is a system test and may trigger a DTC for any fault causing EGR system to fail. DTC associated with this test is DTC P0401. DTC P1408 is similar to P0401, but performed during KOER self-test conditions.
  6. The MIL is activated after one of the above tests fails on 2 consecutive drive cycles.

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