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DTC P0400: Exhaust Gas Recirculation System
 
 
 
 
TECHNICAL DESCRIPTION
  • When the EGR valve (stepper motor) is actuated from the fully closed position toward the open position while the engine is running, EGR gas flows.
  • The ECM checks how the EGR gas flow signal changes.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Small manifold pressure change during exhaust gas recirculation (EGR) operation from closed to open.
 
 
MONITOR EXECUTION
  • Continuous
 
 
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC set in memory for the item monitored below)
  • Exhaust gas recirculation (EGR) stepper motor monitor
Sensor (The sensor below is determined to be normal)
  • Mass airflow sensor
  • Engine coolant temperature sensor
  • Intake air temperature sensor
  • Barometric pressure sensor
  • Manifold absolute pressure sensor
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Conditions
  • More than 10 seconds have passed since the engine starting sequence was completed.
  • At least 20 seconds have passed since the last monitor was complete.
  • Engine coolant temperature is higher than 76°C (169°F).
  • Volumetric efficiency is lower than 40 percent.
  • Barometric pressure is more than 76 kPa (22.4 in.Hg).
  • Intake air temperature is higher than -1°C (30°F).
  • 12V starter battery positive voltage is higher than 10.3 volts.
  • PHEV requested torque is between 71 and 79 N·m.
  • More than 0.5 second has elapsed after the above mentioned conditions have been met.
  • Vehicle speed is higher than 30 km/h (19 mph).
  • Engine speed is between 1,250 and 1,750 r/min.
  • The ECM monitors for this condition for 3 cycles of 4.5 seconds each during the drive cycle.
  • Changes in volumetric efficiency is less than 1.9 percent during monitoring.
Judgment Criterion
  • When the EGR valve opens to the prescribed opening, the intake manifold pressure fluctuation width is less than 2.5 kPa (0.74 in.Hg).
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • None.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 4 .
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Contaminated EGR valve and EGR passage.
  • ECM failed.

 
 
DIAGNOSIS
STEP 1. Check the EGR system
Refer to GROUP 17, Emission Control - Exhaust Gas Recirculation (EGR) System - General Information .
Are there any abnormalities?
Repair it. Then go to Step 4.
Go to Step 2.
 
STEP 2. Check the EGR valve contamination and the EGR passage contamination.
Are the EGR valve and the EGR passage clogged?
Repair the EGR valve and the EGR passage contamination. Then go to Step 4.
Go to Step 3.
 
STEP 3. Check the trouble symptoms.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 4 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0400 set?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 4.
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
 
STEP 4. Test the OBD-II drive cycle.
(1) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 4 .
(2) Check the diagnostic trouble code (DTC).
Is DTC P0400 set?
Retry the troubleshooting.
The inspection is complete.