DTC P0401 [MZR-CD (RF Turbo)]

BME010200400211

DTC P0401

EGR flow insufficient detected

DETECTION CONDITION

• The PCM monitors the difference between the target air amount and intake air amount while the EGR system is operating. If the difference between the target air amount and the intake air amount is less than the threshold, the PCM determines that there is a malfunction in the EGR system.
Diagnostic support note
• MIL illuminates if PCM detects above malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM.
• PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
• FREEZE FRAME DATA is available.
• DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Vacuum hose malfunction
• EGR valve malfunction
• EGR boost sensor malfunction
• EGR gasket malfunction
• PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION

1
VERIFY FREEZE FRAME DATA HAS BEEN RECORDED
• Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record FREEZE FRAME DATA on repair order, then go to the next step.
2
VERIFY RELATED REPAIR INFORMATION AVAILABILITY
• Verify related service bulletins and/or on-line repair information availability.
• Is any related repair information available?
Yes
Perform repair or diagnosis according to the available repair information.
• If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
INSPECT FOR OTHER DTCS
• Connect the WDS or equivalent to the DLC-2.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Turn the engine switch to the ON position. (Engine off).
• Have other DTCs been stored?
Yes
Repair the circuit malfunction for the applicable DTCs.
No
Go to the next step.
4
INSPECT VACUUM HOSE CONDITION
• Inspect the vacuum hoses for clogging, damage, freezing, or vacuum leakage.
• Is there any malfunction?
Yes
Replace the vacuum hoses, then go to Step 8.
No
Go to the next step.
5
INSPECT EGR VALVE MALFUNCTION
• Inspect the EGR valve.
• Is the EGR valve normal?
Yes
Go to the next step.
No
Replace the EGR valve, then go to Step 8.
6
INSPECT EGR BOOST SENSOR MALFUNCTION
• Inspect the EGR boost sensor.
• Is the EGR boost sensor normal?
Yes
Go to the next step.
No
Replace the EGR boost sensor, then go to Step 8.
7
INSPECT EGR VALVE PASSAGE
• Turn the engine switch off.
• Remove the EGR valve.
• Is gasket installation normal?
Yes
Go to the next step.
No
Install the gasket correctly, then go to the next step.
8
VERIFY TROUBLESHOOTING OF DTC P0401 COMPLETED
• Make sure to reconnect all disconnected connectors.
• Connect the WDS or equivalent to the DLC-2.
• Clear the DTC from the PCM memory using the WDS or equivalent.
• Perform the Repair Verification Drive Mode.
• Is the PENDING CODE for this DTC present?
Yes
Go to the next step.
No
Replace the PCM, then go to the next step.
9
VERIFY AFTER REPAIR PROCEDURE
• Are any DTCs present?
Yes
Go to the applicable DTC inspection.
No
Troubleshooting completed.