LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Infiniti >> 2001 >> Q45 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0400: EGR Function >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0400: EGR Function: Procedure

  1. Check exhaust system for leaks. Repair as necessary and retest system. If no leaks are found, start engine and warm to normal operating temperature. Turn ignition off. Raise drive wheels and support vehicle. Start engine. Ensure TCS switch is in OFF position. Shift transmission into first gear. Disconnect vacuum hose from EGR valve. Check for vacuum at hose. Vacuum should not exist. Increase engine speed to 3000 RPM. Vacuum should exist while revving engine. If vacuum is as specified, go to next step. If vacuum is not as specified, go to step  3.
  2. Turn ignition off. Remove EGR valve. Using a hand vacuum pump, apply vacuum to EGR valve. EGR valve should lift. Release vacuum. EGR valve should close. Clean or replace EGR valve as necessary and retest system.
  3. Turn ignition off. Check vacuum hoses for leaks, blockage or misrouting. See VACUUM DIAGRAMS article. Repair as necessary and retest system. If vacuum hoses are okay, go to next step.
  4. Turn ignition off. Disconnect ECM harness connector. See Figure. Connect a jumper wire between engine ground and ECM harness connector terminal No. 10. See Figure. Turn ignition on and listen for EGRC solenoid operating sound. If EGRC solenoid clicks, go to next step. If EGRC solenoid does not click, repair EGRC solenoid or circuit and retest system. See DTC P1400: EGRC SOLENOID .
  5. Remove EGRC solenoid. See Figure. Using jumper wires, apply battery voltage between EGRC solenoid terminals. See Figure. Air should flow between ports "A" and "B". Air should not flow between ports "A" and "C". Remove jumper wires. Air should not flow between ports "A" and "B". Air should flow between ports "A" and "C". EGRC solenoid should switch in one second or less. If operation is as specified, go to next step. If operation is not as specified, replace EGRC solenoid and retest system.
  6. Check EVAP canister. See SYSTEM & COMPONENT TESTING article. Replace, if necessary and retest system. If EVAP canister is okay, check EVAP system vacuum hoses for leaks, blockage or misrouting. See VACUUM DIAGRAMS article. Repair as necessary and retest system. If vacuum hoses are okay, go to next step.
  7. Remove EGRC-BPT. Plug one vacuum port and apply vacuum to other vacuum port. Vacuum should not hold. Apply 3.94 in. H2 O (.98 kPa) of pressure to backpressure port. Vacuum should hold. If operation is as specified, go to next step. If operation is not as specified, replace EGRC-BPT and retest system.
  8. Remove EGR temperature sensor. See Fig 1. Measure resistance between EGR temperature sensor terminals, with sensor at specified temperatures. See EGR TEMPERATURE SENSOR RESISTANCE  table. If resistance is as specified, go to next step. If resistance is not as specified, replace EGR temperature sensor and retest system.
  9. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
EGR TEMPERATURE SENSOR RESISTANCE

Temperature - °F (°C) K/Ohms
0 (32) 680-1110
50 (122) 90-120
100 (212) 17-24
Fig 1: Locating EGR Temperature Sensor Harness Connector
G97B06700Courtesy of NISSAN MOTOR CO., U.S.A.
scientia non olet · About LEMON Manuals