OBD2 Code P0401: Auxiliary Emissions (EGR, EVAP, Catalyst)
Emissions control system fault.
Detected Root Component
EGR Valve
Technical Component Diagrams
EGR Valve Layout
Diag Expert technical diagram
EGR Valve Connector
Diag Expert technical diagram
Observed Symptoms
- Engine light on (MIL/Check Engine)
- Emissions exceeding standards
- Excessive fuel consumption
- Strong exhaust smell
Possible Causes
- Clogged EGR valve
- EGR channel clogged
- Failed catalyst
- Vacuum leak
- Faulty solenoid valve
Tools Required
Interactive Diagnostic
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Diagnostic Result
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Parts likely to be the cause (Vanne EGR)
Vanne EGR
Photo d'illustration : Vanne EGR
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Frequently asked questions about code P0401
What does code P0401 mean? ▾
OBD2 Code P0401: Auxiliary Emissions (EGR, EVAP, Catalyst). Emissions control system fault.
What are the symptoms of code P0401? ▾
Code P0401 may cause: Engine light on (MIL/Check Engine), Emissions exceeding standards, Excessive fuel consumption, Strong exhaust smell. The intensity of these symptoms varies depending on the vehicle and driving conditions.
What causes code P0401? ▾
The most common causes of code P0401 are: Clogged EGR valve, EGR channel clogged, Failed catalyst, Vacuum leak. A proper OBD2 diagnostic will pinpoint the exact cause.
Is it serious to drive with code P0401? ▾
Code P0401 has moderate severity (Warning). Short-term driving remains possible, but a prompt check is recommended to prevent worsening.
How do I fix code P0401? ▾
Start by reading the code with an OBD2 scanner, then follow the interactive decision tree on this page. Priority causes to check: Clogged EGR valve, EGR channel clogged, Failed catalyst, Vacuum leak. Difficulty: Medium · Estimated time: 45-90min.