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Home >> Nissan-Datsun >> 2000 >> Altima GXE L4-2.4L (KA24DE) >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> P Code Charts >> P0400

P0400







SYSTEM DESCRIPTION
This system cuts and controls vacuum applied to the EGR valve to suit engine operating conditions. This cut-and-control operation is accomplished through the ECM and the EGRC-solenoid valve. When the ECM detects any of the following conditions, the ECM cuts the current for the solenoid valve. This causes the port vacuum to be discharged into the atmosphere. The EGR valve remains closed.
- Low engine coolant temperature
- Engine starting
- High-speed engine operation
- Engine idling
- Excessively high engine coolant temperature
- Mass air flow sensor malfunction
- Low ambient temperature

COMPONENT DESCRIPTION




Exhaust gas recirculation (EGR) valve
The EGR valve controls the amount of exhaust gas routed to the intake manifold. Vacuum is applied to the EGR valve in response to throttle valve opening. The vacuum controls the movement of a taper valve connected to the vacuum diaphragm in the EGR valve.




EGRC-solenoid valve
The EGRC-solenoid valve responds to signals from the ECM. When the ECM sends an ON (ground) signal, the coil in the solenoid valve is energized.
A plunger will then move to cut the vacuum signal from the intake manifold to the EGR valve. When the ECM sends an OFF signal, the vacuum signal passes through the solenoid valve. The signal then reaches the EGR valve.







ON BOARD DIAGNOSIS LOGIC
If the absence of EGR flow is detected by EGR temperature sensor under the condition that calls for EGR, a low-flow malfunction is diagnosed.










DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE

CAUTION: Always drive vehicle at a safe speed.

NOTE:
- If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.
- During the test, P0400 will not be stored in ECM even though "NG" is displayed on the CONSULT-II screen.

TESTING CONDITION: For best results, perform test at a temperature above 5°C (41°F) or higher.

With Consult
1. Turn ignition switch "ON"
2. Check "COOLAN TEMP/S" in "DATA MONITOR" mode witch CONSULT-II.
Confirm COOLAN TEMP/S value is within the range listed below.
COOLANT TEMP/S: Less than 40°C (104°F)
If the value is out of range, park the vehicle in a cool place and allow the engine temperature to stabilize. Do not attempt to lower the coolant temperature with a fan or means other than ambient air. Doing so may produce an inaccurate diagnostic result.
3. Turn ignition switch "ON" and select "EGR SYSTEM P0400" of "EGR SYSTEM" in "DTC WORK SUPPORT" mode with CONSULT-II.
4. Touch "START".
5. Start engine and let it idle. When the engine coolant temperature reaches 70°C (158°F), immediately go to the next step.
6. Accelerate vehicle to a speed of 40 kph (25 MPH) once and then stop vehicle.
If "COMPLETED" with "OK" appears on CONSULT-II screen, go to step 9.
If "COMPLETED" does not appear on CONSULT-II screen, go to the following step.
7. Check the output voltage of "THRTL POS SEN" (at closed throttle position) and note it.
8. When the following conditions are met, �TESTING" will be displayed on the CONSULT-II screen. Maintain the conditions until "TESTING" changes to "COMPLETED". (It will take approximately 50 seconds or more.)
CMPS-RPM (REF): 1,500 - 2,500 rpm (A/T) 2,000 - 3,000 rpm (M/T)
Vehicle speed: 10 kph (6 MPH) or more
B/FUEL SCHDL: 2.8 - 3.4 msec (A/T) 2.1 - 2.6 msec (M/T)
THRTL POS SEN: X - (X + 4.5) V
X = Voltage value measured at step 7)
Selector lever: Suitable position
If "TESTING" is not displayed after 5 minutes, retry from step 2.
9. Make sure that "OK" is displayed after touching "SELF-DIAG RESULTS". If "NG" is displayed, refer to "Diagnostic Procedure" below.













OVERALL FUNCTION CHECK
Use this procedure to check the overall EGR function. During this check, a 1st trip DTC might not be confirmed.

Without Consult
1. Start engine and warm it up to normal operating temperature.
2. Check the EGR valve lifting when rewing from 2,000 rpm up to 4,000 rpm under no load using the following methods.
EGR valve should lift up and down without sticking.
If NG, go to E in DIAGNOSTIC PROCEDURE.
3. Check voltage between EGR temperature sensor harness connector terminal (1) and ground at idle speed.
Less than 4.5V should exist.
4. Turn ignition switch "OFF ".
5. Check harness continuity between EGR temperature sensor harness connector terminal (2) and ECM terminal (50).
Continuity should exist
6. Perform "COMPONENT INSPECTION", "EGR temperature sensor".

EC-EGRC1-01:




EC-EGRC1-01 - Connector View:




WIRING DIAGRAM

Diagnostic Procedure (Part 1 Of 2):




Diagnostic Procedure (Part 2 Of 2):




DIAGNOSTIC PROCEDURE

COMPONENT INSPECTION




EGR valve
Apply vacuum to EGR vacuum port with a hand vacuum pump.

EGR valve spring should lift
Check for sticking.
If NG, repair or replace EGR valve.







EGRC-solenoid valve
Check air passage continuity.

With Consult
Perform "EGRC SOLENOID VALVE" in "ACTIVE TEST" mode.

OR







Without Consult
If NG or operation takes more than 1 second, replace EGRC solenoid valve.




EGR temperature sensor
Check resistance change and resistance value.




Reference Data:




If NG, replace EGR temperature sensor.




EGRC-BPT valve
1. Plug one of two ports of EGRC-BPT valve.
2. Vacuum from the other port and check for leakage while applying a pressure above 0.981 kPa (100 mmH(2)O, 3.94 inH(2)O) from under EGRC-BPT valve.
3. If a leakage is noted, replace the valve.
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