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DTC P0400: EGR Function

  1. Check Power Supply  - Turn ignition off. Turn ignition on. Measure voltage between EGR temperature sensor connector terminal No. 1 and ground. Voltage should be less than 4.5 volts. Measure voltage between ECM connector terminals No. 25 and 59. Voltage should be more than 2.4 volts. If voltage is as specified, go to next step. If voltage is not as specified, repair harness as necessary.
  2. Check Input Signal  - Turn ignition off. Check for conrtinuity between EGR temperature sensor connector terminal No. 2 and ECM connector terminal No. 43. If continuity is present, go to next step. If continuity is not present, repair harness or connectors as necessary.
  3. Check Vacuum Source To EGR Valve  - Start engine and bring to operating temperature. With engine speed at 2000-4000 RPM, disconnect vacuum hose to EGR valve. If vacuum is not present, go to next step. If vacuum is present, inspect EGR valve. See SYSTEM/COMPONENT TESTS article. Service or replace components if necessary and perform FINAL CHECK.
  4. Check EGRC Solenoid  - Turn ignition on. Check operating sound of EGRC solenoid while disconnecting and reconnecting EGRC solenoid harness connector. If solenoid is not functioning properly, repair or replace solenoid as required. If solenoid is functioning properly, go to next step.
  5. Disconnect EGRC solenoid. Apply battery voltage and ground to terminals No. 1 and 2. See Fig 1. With battery voltage applied, air should pass between ports "A" and "B". Air should not pass between ports "A" and "C". With no voltage applied, air should pass between ports "A" and "C". Air should not pass between ports "A" and "B". Replace EGRC solenoid if airflow is not as specified. If solenoid is okay, check vacuum hoses for restrictions or misrouting.
  6. Check EGR Temperature Sensor  - Measure resistance of EGR temperature sensor. See EGR TEMPERATURE SENSOR RESISTANCE table. If EGR temperature sensor is okay, disconnect harness connectors in circuit and check for damage or corrosion. If fault is still present, go to DTC P0402: EGR CONTROL BACKPRESSURE TRANSDUCER (EGRC-BPT) VALVE.
EGR TEMPERATURE SENSOR RESISTANCE (1)

Temperature - °F (°C) Volts Ohms
32 (0) 4.81 7.9-9.7
122 (50) 2.82 0.57-0.70
212 (100) 0.8 0.08-0.10
(1) Megohms are given.
Fig 1: Checking EGRC Solenoid Valve
G96B10505Courtesy of NISSAN MOTOR CO., U.S.A.
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