P0401
DTC P0401 EXHAUST GAS RECIRCULATION FLOW INSUFFICIENT DETECTEDCIRCUIT DESCRIPTION
DTC Detection Condition:
The EGR system recirculates exhaust gas, which is controlled to the proper quantity to suit the driving conditions, into the intake air mixture so as to slow down the combustion, reduce the combustion temperature and reduce NOx emissions.
The lift amount of the EGR valve is controlled by the vacuum, which is regulated by the Duty-VSV operated by the ECM. The lift amount of EGR valve is detected by the EGR valve position sensor which is mounted on the EGR valve and it provides feedback to the ECM to control the lift amount of EGR valve in response to engine operating conditions.
Under the following conditions, EGR is cut to maintain driveability.
- Before the engine is warmed up
- During deceleration (throttle valve closed)
- Light engine load (amount of intake air very small)
- Engine speed over 4,000 rpm
- Engine idling
Wiring Diagram:
SYSTEM CHECK DRIVING PATTERN
System Check Driving Pattern:
a. Connect the OBD II scan tool or hand-held tester to the DLC3.
b. Start and warm up the engine with all the accessories switched OFF.
c. Run the vehicle at 70 - 90 km/h (43 - 56 mph) for 3 minutes or more.
d. Idle the engine for about 2 minutes.
e. Do steps (c) and (d) again.
f. Stop in a safe place and turn the ignition switch OFF.
g. Do step (b) to (e) again.
h. Check the READINESS TESTS mode on the OBD II scan tool or hand-held tester.
If COMPL is displayed and the MIL does not light up, the system is normal
If INCMPL is displayed and the MIL does not light up, run the vehicle steps (b) to (f) from some times and check it.
HINT: INCMPL is displayed when either condition (1) or (2) exists.
1. The system check is incomplete.
2. There is a malfunction in the system.
If there is a malfunction in the system, the MIL light up after step (g) above is done (2 trip detection logic).
INSPECTION PROCEDURE
HINT: Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.
Step 1:
Step 2 - 3:
Step 4 - 8:
Step 9 - 10:
Hand-held Tester:
Step 1 - 2:
Step 3 - 6:
Step 7 - 9:
OBD II scan tool (excluding Hand-held Tester):