P0400
TECHNICAL DESCRIPTION- When the EGR solenoid switches from "OFF" to "ON" while the engine is running, EGR gas flows.
- The PCM checks how the EGR gas flow signal changes.
DTC SET CONDITIONS
Check Area
- At least twenty seconds have passed since the last monitor was complete.
- Engine coolant temperature is higher than 80° C (176° F).
- Engine speed is at between 910 and 1,650 r/min.
- Intake air temperature is higher than 5° C (41° F).
- Barometric pressure is higher than 76 kPa (11 psi).
- Vehicle speed is 30 kph (18.7 mph) or more.
- At least ninety seconds have passed since manifold differential pressure sensor output voltage fluctuated 1.5 volts or more.
- The throttle valve is closed.
- Volumetric efficiency is lower than 28 percent.
- Monitoring time: 2 seconds.
Judgment Criteria
- The intake manifold pressure fluctuations are minimal. When the EGR solenoid is turned ON.
- Three monitors during one drive cycle
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- EGR valve does not open.
- EGR control vacuum is too low.
- EGR solenoid failed.
- Open or shorted EGR solenoid circuit, or loose connector.
- Manifold differential pressure sensor failed.
- PCM failed.
DIAGNOSIS
Required Special Tool:
MB991502: Scan Tool (MUT-II)
STEP 1. Check the EGR system
Refer to Emission Control System.
If correct, go to Step 2.
If incorrect, repair or replace. Then go to Step 3.
CAUTION: To prevent damage to the scan tool, turn the ignition switch "OFF" before connecting or disconnecting the scan tool.
STEP 2. Using scan tool MB991502, check data list item 95: Manifold Differential Pressure Sensor.
- Should be between 22.6 and 36.0 kPa at engine idling. If not within specifications, refer to DTC P1400 - Manifold Differential Pressure Sensor Circuit Malfunction.
If within specifications, clean the EGR valve and EGR passage. Then go to Step 3.
STEP 3. Test the OBD-II drive cycle
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 5 - Exhaust Gas Recirculation (EGR) System Monitor.
2. Read the diagnostic trouble code, and confirm that a diagnostic trouble code is not being output.