P0401 — EGR Flow Insufficient Detected
Seen on: All EGR-equipped diesel engines
EGR Flow Insufficient Detected. Common causes: Plugged EGR cooler, stuck EGR valve, restricted EGR passages.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Caution. Limp to the next safe stop.
Most likely causes
- Plugged EGR cooler
- stuck EGR valve
- restricted EGR passages
- EGR delta pressure sensor fault
- EGR bypass valve
FAQ
EGR Flow Insufficient Detected. Common causes: Plugged EGR cooler, stuck EGR valve, restricted EGR passages.
Caution — Limp to the next safe stop.
The most common cause is: Plugged EGR cooler. Other possibilities include stuck EGR valve; restricted EGR passages; EGR delta pressure sensor fault; EGR bypass valve.
Limp to the next safe stop. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.