DTC P0401:00 [PCM (SKYACTIV-G 2.5T)]

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Note
•  To determine the malfunctioning part, proceed with the diagnostics from “Function Inspection Using M-MDS”.

Details On DTCs

DESCRIPTION

EGR flow insufficient detected
DETECTION CONDITION
Determination conditions
•  When the following condition is met, the EGR volume is lower than the specification for the target value for a continuous specified time.
Preconditions
•  Intake air temperature: -3.0 °C {37 °F} or more
•  Engine coolant temperature: -65.0 °C {149 °F} or more
•  Engine speed: 1,400—3,000 rpm
•  Purge control: not active
•  Fuel injection control: during fuel cut
•  The following DTCs are not detected:
?  TP sensor: P0122:00, P0123:00, P2135:00
?  ECT sensor: P0116:00, P0117:00, P0118:00
?  MAP sensor: P0069:00, P0107:00, P0108:00
?  EGR valve control system: P0403:00
?  MAF sensor: P0101:00, P0102:00, P0103:00
?  Exhaust gas pressure sensor: P0472:00, P0473:00
?  Boost pressure sensor: P0237:00, P0238:00
?  HO2S: P013A:00
Drive cycle
•  2
Self test type
•  CMDTC self test
Sensor used
•  EGR valve
•  MAF sensor
•  MAP sensor
•  Exhaust gas pressure sensor
FAIL-SAFE FUNCTION
•  Inhibits engine-stop by operating the i-stop function.
VEHICLE STATUS WHEN DTCs ARE OUTPUT
•  Not applicable
POSSIBLE CAUSE
•  Erratic signal to PCM
?  MAF sensor signal malfunction
?  MAP sensor signal malfunction
?  Input signal part connector or terminals malfunction
?  Input signal part related circuit malfunction
•  EGR valve malfunction (stuck close)
•  Air suction in intake air system between dynamic pressure turbo (DPT) and intake manifold
•  EGR system passage malfunction (restriction)
•  Exhaust gas pressure sensor malfunction
•  PCM malfunction

System Wiring Diagram

•  Not applicable

Function Explanation (DTC Detection Outline)

•  The PCM compares the target EGR flow volume with the estimated EGR flow volume and performs diagnosis of the EGR system.
•  The PCM opens the EGR valve when all of the preconditions are met. The PCM compares the target EGR flow volume with the estimated EGR flow volume at that time, if the estimated EGR flow volume is smaller than the target EGR flow volume, a malfunction is determined.
•  The PCM performs diagnosis when each of the preconditions during drive cycle is met. If a malfunction is detected, the malfunction detection counter begins counting up. The value of the malfunction detection counter is maintained while the preconditions are not being met. If the cumulative value of the malfunction detection counter exceeds the threshold during the first drive cycle, a malfunction is determined and a pending code is stored.
•  If the calculated value of the malfunction detection counter during one drive cycle exceeds the threshold, the PCM determines a malfunction, stores a DTC and turns on the check engine light.
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Repeatability Verification Procedure

Caution
•  When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later.
•  While performing this step, always operate the vehicle in a safe and lawful manner.
1.  Start the engine and warm it up until the engine coolant temperature exceeds 60 °C {140 °F}.
2.  Start the engine, race it at 4,000 rpm, and idle it.
3.  Repeat Step 2 operation above 2 times.

PID Item/Simulation Item Used In Diagnosis

PID/DATA monitor item table

Item

Definition

Unit

Condition/Specification
MAF
Mass air flow input from MAF sensor
g/Sec
•  Displays MAF
MAF sensor voltage
V
•  Ignition switched ON (engine off) (MAF: 0.59 g/s {0.078 lb/min}): Approx. 0.72 V
•  Idle (after warm up) (MAF: 2.17 g/s {0.287 lb/min}): Approx. 0.97 V
•  Racing (engine speed is 2,000 rpm) (MAF: 4.73 g/s {0.626 lb/min}): Approx. 1.26 V
MAP
Manifold absolute pressure input from MAP sensor
KPa {MPa}, mBar {Bar}, psi, in H20
•  Displays MAP
MAP_V
MAP sensor voltage
V
•  Ignition switched ON (engine off) (no load) (MAP: 102 kPa {1.04 kgf/cm2, 14.8 psi}): Approx. 1.75 V
•  Idle (after warm up) (no load) (MAP: 30 kPa {0.31 kgf/cm2, 4.4 psi}): Approx. 0.68 V
•  Racing (engine speed is 2,000 rpm) (no load) (MAP: 27 kPa {0.28 kgf/cm2, 3.9 psi}): Approx. 0.61 V

Function Inspection Using M-MDS

STEP

INSPECTION

ACTION
1
PURPOSE: RECORD VEHICLE STATUS AT TIME OF DTC DETECTION TO UTILIZE WITH REPEATABILITY VERIFICATION
Note
•  Recording can be facilitated using the screen capture function of the PC.
•  Record the snapshot data on the repair order.
—
Go to the next step.
2
PURPOSE: VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
PURPOSE: IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
•  Is the DTC P0401:00 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to the troubleshooting procedure for DTC on FREEZE FRAME DATA.
(See DTC TABLE [PCM (SKYACTIV-G 2.5T)].)
4
PURPOSE: VERIFY IF DIAGNOSTIC RESULT IS AFFECTED BY OTHER RELATED DTCs OCCURRING
•  Switch the ignition off, then ON (engine off).
•  Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure.
•  Is the other PENDING CODE/DTC also present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.5T)].)
No
Go to the next step.
5
PURPOSE: VERIFY IF THERE IS PID ITEM CAUSING DRASTIC CHANGES OF ACCELERATION FLUCTUATION BY INPUT SIGNAL TO PCM
•  Access the following PIDs using the M-MDS:
PCM:
?  MAF
?  MAP
?  MAP_V
•  Is there any signal that is far out of specification?
Yes
Go to the next step.
No
Go to the troubleshooting procedure to perform the procedure from Step 1.
6
PURPOSE: VERIFY CONNECTOR CONNECTIONS
•  Access the following PIDs using the M-MDS:
PCM:
?  MAF
?  MAP
?  MAP_V
•  When the following parts are shaken, does the PID value include a PID item which has changed?
?  MAF sensor
?  MAP sensor
?  PCM
Yes
Repair or replace the applicable connector parts.
Go to the troubleshooting procedure to perform the procedure from Step 5.
No
Go to the troubleshooting procedure to perform the procedure from Step 1.


Troubleshooting Diagnostic Procedure

Intention of troubleshooting procedure
•  Step 1
?  Perform inspection of each separate part.
•  Step 2—3
?  Perform inspection of EGR valve passage
•  Step 4
?  Perform a unit inspection of the exhaust gas pressure sensor.
•  Step 5—6
?  Verify that the primary malfunction is resolved and there are no other malfunctions.

STEP

INSPECTION

ACTION
1
PURPOSE: INSPECT EGR VALVE CONTROL SYSTEM OPERATION
•  Perform the EGR Valve Operation Inspection.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 5.
No
Go to the next step.
2
PURPOSE: INSPECT INTAKE AIR SYSTEM FOR AIR SUCTION
•  Inspect for air leakage at the following:
?  Around connection of dynamic pressure turbo (DPT) and intake manifold
Note
•  Engine speed may change when rust penetrating agent is sprayed on the air suction area.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 5.
No
Go to the next step.
3
PURPOSE: INSPECT FOR RESTRICTION OR CLOGGED IN EGR PASSAGE
•  Switch the ignition off.
•  Remove the EGR valve.
•  Visually inspect the EGR passage for clogging and the gasket correctly installed.
•  Is there any malfunction?
Yes
Repair or replace the malfunctioning part according to the inspection results, then go to Step 5.
(If there is clogging caused by soot in the EGR valve, inspect around the EGR piping and clean or replace it.)
No
Go to the next step.
4
PURPOSE: DETERMINE INTEGRITY OF EXHAUST GAS PRESSURE SENSOR
•  Inspect the exhaust gas pressure sensor.
•  Is there any malfunction?
Yes
Replace the exhaust gas pressure sensor, then go to the next step.
(See EXHAUST GAS PRESSURE SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5T].)
No
Go to the next step.
5
PURPOSE: PERFORM DTC INSPECTION AND VERIFY IF MALFUNCTIONING PART IS PCM
•  Always reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Implement the repeatability verification procedure.
•  Perform the Pending Trouble Code Access Procedure.
•  Is the PENDING CODE for this DTC present?
Yes
Repeat the inspection from Step 1.
•  If the malfunction recurs, replace the PCM.
Go to the next step.
No
Go to the next step.
6
PURPOSE: VERIFY AFTER REPAIR PROCEDURE
•  Perform the “AFTER REPAIR PROCEDURE”.
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [PCM (SKYACTIV-G 2.5T)].)
No
DTC troubleshooting completed.