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

DTC detecting condition: 

Detected when two consecutive driving cycles with fault occur.

Trouble symptom: 

• Infrequent knocking (P0401)
• Improper idling (P0402)
• Movement performance problem (P0402)

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) (H4DOTC)>Diagnostic Trouble Code (DTC)>LIST .

No 

• DTC P0401 displayed: Go to  2.
• DTC P0402 displayed: Go to  3.

1. Turn the ignition switch to OFF.
2. Check for clogging in the pipes consisting of 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.

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 and intake air temperature sensor
   • Foreign matter attached to EGR valve

Is the check result OK?

Yes  : Go to  4.

No  : Clean and replace the faulty parts.

Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DOTC)>INSPECTION MODE .

Does the malfunction indicator light illuminate?

Yes  : Replace the EGR control valve and manifold absolute pressure and intake air temperature sensor. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DOTC)>EGR Control Valve>REMOVAL . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DOTC)>Manifold Absolute Pressure and Intake Air Temperature Sensor>REMOVAL .

No  : End.