P0401: Exhaust Gas Recirculation Flow Insufficient
91 vehicles · 21 makes
P0401 is an OBD-II diagnostic trouble code meaning “Exhaust Gas Recirculation Flow Insufficient.” The EGR system is not flowing enough exhaust gas back into the intake. Usually caused by carbon buildup in the EGR valve or passages. This code appears across 91 vehicle models from 21 manufacturers.
Common Causes
Diagnostic Tools
To diagnose P0401, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
- Read & clear engine codes
- View freeze frame data
- I/M readiness status
- No batteries or app needed
BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
- Enhanced diagnostics (ABS, SRS, transmission)
- Repair Reports with verified fixes
- Smog check readiness
- Free app (iOS & Android)
LAUNCH CRP123X OBD-II Scanner
by LAUNCH
A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
- Engine, transmission, ABS, SRS diagnostics
- Live data stream & graphing
- AutoVIN for vehicle identification
- Free lifetime updates via Wi-Fi
Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
- All-system diagnostics (25+ modules)
- Bi-directional control & active tests
- Oil reset, EPB, BMS, TPMS, injector coding
- 7-inch touchscreen with Android OS
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Vehicles Affected (91)
FAQ
What does P0401 mean?
P0401 stands for "Exhaust Gas Recirculation Flow Insufficient." The EGR system is not flowing enough exhaust gas back into the intake. Usually caused by carbon buildup in the EGR valve or passages.
What are the most common causes of P0401?
The most common causes of P0401 are: Carbon buildup in EGR valve, Clogged EGR passages in intake manifold, Failed EGR valve, Faulty DPFE/EGR pressure sensor, Vacuum supply issue to EGR. The specific cause varies by vehicle.
How much does it cost to fix P0401?
Repair costs vary widely depending on the root cause and vehicle.
Which vehicles are affected by P0401?
Au7o has documented P0401 across 91 vehicle models from 21 manufacturers: Audi, BMW, Cadillac, Chrysler, Citroën, Dodge, Ford, GMC, Honda, Hyundai, Jeep, Kia, Land Rover, Mazda, Nissan, Peugeot, RAM, Subaru, Toyota, Volkswagen, Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.