P0401 — EGR Flow Insufficient Detected
What it means: EGR Flow Insufficient Detected.
How serious / can you keep driving: Caution. Limp to the next safe stop.
Check first: Start with the most likely cause: Plugged EGR cooler.
Don't risk it — look up listed providers near you and give them this code when you call.
Listed providers nearest Oklahoma City, OK
Closest first. Tell them P0401 and what the truck is doing. RoadService.app lists these providers and does not employ them or carry out the repair.
- 0.0 mi away — based in Oklahoma City, OK · (405) 551-3320
- 0.0 mi away — based in Oklahoma City, OK · (405) 682-1362
- 0.0 mi away — based in Oklahoma City, OK · (405) 632-6010
Seen on: All EGR-equipped diesel engines
What P0401 means
EGR Flow Insufficient Detected. Common causes: Plugged EGR cooler, stuck EGR valve, restricted EGR passages.
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.
Related codes
Codes that commonly appear alongside P0401, or share the same subsystem.
- SCR Operator Inducement — Severe Derate Active (SPN 5246 FMI 0)
- Aftertreatment 1 Diesel Particulate Filter Differential Pressure - Data Valid But Above Normal Operating Range, Most Severe Level (DPF severely restricted / plugged) (SPN 3251 FMI 0)
- Aftertreatment 1 Diesel Exhaust Fluid Quality - Data Valid But Below Normal Operating Range, Most Severe Level (DEF quality/concentration incorrect) (SPN 4364 FMI 1)
- DPF Differential Pressure — Data Erratic (SPN 3251 FMI 2)
- DEF Dosing Unit — Not Responding Properly (SPN 3361 FMI 7)
- SCR Conversion Efficiency — Below Threshold (SPN 4364 FMI 18)
- DEF Quality — Out of Spec (SPN 4094 FMI 31)
- EGR Temperature — Too High (SPN 412 FMI 0)
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.