OBD2 code P0402: EGR A Flow Excessive Detected
Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx.
Detected Root Component
EGR Valve
Technical Component Diagrams
EGR Valve Layout
Diag Expert technical diagram
EGR Valve Connector
Diag Expert technical diagram
Observed Symptoms
- Check engine light on
- Rough idle or stalling (petrol)
- Jerking at part load
- Diesel: black smoke, loss of power
Possible Causes
- EGR valve stuck open, dirt under the seat
- Ford: DPFE sensor drifting or hose wrong
- Diesel: air leak between air mass meter and turbo, MAF drift
- Valve control opens unintentionally
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 P0402
What does code P0402 mean? ▾
OBD2 code P0402: EGR A Flow Excessive Detected. Exhaust gas recirculation (EGR) routes part of the exhaust back into the intake to lower combustion temperature and NOx.
What are the symptoms of code P0402? ▾
Code P0402 may cause: Check engine light on, Rough idle or stalling (petrol), Jerking at part load, Diesel: black smoke, loss of power. The intensity of these symptoms varies depending on the vehicle and driving conditions.
What causes code P0402? ▾
The most common causes of code P0402 are: EGR valve stuck open, dirt under the seat, Ford: DPFE sensor drifting or hose wrong, Diesel: air leak between air mass meter and turbo, MAF drift, Valve control opens unintentionally. A proper OBD2 diagnostic will pinpoint the exact cause.
Is it serious to drive with code P0402? ▾
Code P0402 has moderate severity (Warning). Short-term driving remains possible, but a prompt check is recommended to prevent worsening.
How do I fix code P0402? ▾
Start by reading the code with an OBD2 scanner, then follow the interactive decision tree on this page. Priority causes to check: EGR valve stuck open, dirt under the seat, Ford: DPFE sensor drifting or hose wrong, Diesel: air leak between air mass meter and turbo, MAF drift, Valve control opens unintentionally. Difficulty: Medium · Estimated time: 30-60min.