DTC P0401: EGR Abnormal (EGR Amount Too Small): Notes

WARNING: This page is about a different variant/trim than selected.

-
DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:
- Infrequent knocking (P0401)
- Improper idling (P0402)
- Movement performance problem (P0402)
  NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine]. Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .
Are DTCs other than P0401 and P0402 displayed? (Current malfunction)

Yes: Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>DIAGNOSTIC TROUBLE CODE (DTC) .

No:
- DTC P0401 displayed: Go to 2.
- DTC P0402 displayed: Go to 3.
CHECK DTC P0401 .
1. Turn the ignition switch to OFF.
2. Check for clogging in the pipes consisting of the EGR system.
  NOTE:
  Check the following items.
  - Throttle valve
  - EGR cooler
  - EGR control valve
  - EGR pipe
  - EGR pipe adapter
Is the check result OK?

Yes: Go to 4.

No: Clean and replace the faulty parts.
CHECK DTC P0402 .
1. Turn the ignition switch to OFF.
2. Check for leakage in the pipes consisting of the EGR system.
  NOTE:
  Check the following items.
  - Looseness of each flange connection
  - Improper installation of throttle body
  - Improper installation of manifold absolute pressure sensor
  - Foreign matter attached to EGR valve
Is the check result OK?

Yes: Go to 4.

No: Clean and replace the faulty parts.
CHECK FOR REPRODUCTION OF FAILURE .
Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DO 2.0 (EXCEPT FOR HEV))>INSPECTION MODE .

Does the malfunction indicator light illuminate?

Yes: Replace the EGR control valve and manifold absolute pressure sensor. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DO (EXCEPT FOR HEV))>EGR CONTROL VALVE . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO (EXCEPT FOR HEV))>MANIFOLD ABSOLUTE PRESSURE SENSOR .

No: End.