P0401 Exhaust Gas Recirculation Flow Insufficient Detected
What does P0401 mean?
P0401 — Exhaust Gas Recirculation Flow Insufficient Detected. This is an OBD-II diagnostic trouble code a scanner retrieves when your vehicle's computer detects exhaust gas recirculation flow insufficient detected. The level of risk depends on how the vehicle is currently running and how long you've been driving with the light on.
Common causes of P0401
- Carbon buildup blocking the EGR valve or passages
- Faulty EGR valve not opening properly
- Blocked or restricted EGR tubes
- Faulty EGR position sensor
- Vacuum or electrical issues with the EGR system
How to fix P0401
- Remove and inspect the EGR valve for carbon buildup
- Command the EGR valve open with an OBD-II scanner and watch the position response
- Check EGR passages and tubes for blockage
- Verify vacuum supply or electrical control to the valve
- Clean or replace the EGR valve and decarbonize the passages