P0401: Exhaust Gas Recirculation Flow Insufficient
78 vehicles · 23 makes · $20-$15,000 repair
Most Reported On
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 is most commonly reported on 2007-2021 Toyota Tundra (1794 Edition, Base, Limited, Platinum, SR, SR5, TRD Pro), 2011-2023 Nissan Leaf, and 2004-2015 Toyota Prius, plus 75 other vehicles, with repair costs ranging from $20 to $15,000.
Common Causes
Typical Repair Cost
Based on 91 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
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
As an Amazon Associate, we earn from qualifying purchases. Prices are approximate and may vary.
Vehicles Affected (78)
6.7L Power Stroke EGR Cooler Clogging and Failure
12V Battery Drain and Loss of Drive Power - Recall 24S24 + SSM 53087
Driveshaft Carrier Bearing Failure
360-Degree / Rearview Camera System Failure
6.0L Powerstroke EGR Cooler Rupture and Coolant Leak
8L90 8-Speed Torque Converter Shudder
6T40/6T45 6-Speed Transmission Shudder and Harsh Shifts
9T65 9-Speed Transmission Harsh Shifts and Hesitation
8L45 8-Speed Transmission Torque Converter Shudder
EGR Cooler Failure and Coolant Contamination (Duramax LMM/LML)
Front Axle Disconnect Actuator and IWE Hub Failure (4WD Engagement Issues)
1.5T CVT Transmission Judder and Valve Body Failure
CVT Shudder/Judder During Acceleration
CVT Shudder/Judder During Acceleration
IMA Hybrid Battery Pack Failure and Reduced Performance
Premature Engine Mount Failure Causing Vibration
Hybrid Inverter/Power Control Unit (PCU) Cooling System Failure
Hybrid Power Loss While Driving
Type R Limited Slip Differential Noise and Chattering
Soft Top Tears and Rips
Sunroof/Hatch Water Leaks (SC Models)
Tailgate/Liftgate Hinge and Lift Support Problems
Electrical System Issues and Starter Failures
IMA Hybrid Battery Failure (All Generations)
EGR System Clogging (Lean Burn Engine)
ICCU Failure and 12V Battery Drain
Hybrid High-Voltage Battery Degradation
Headlight and Taillight Moisture Condensation
Regenerative Braking Loss and Reduced Braking Power
Onboard Charger (OBC) Failure (Niro EV)
Subframe and Underbody Rust / Corrosion
Rear Brake Caliper Seizing / Parking Brake Cable Corrosion
Rear Brake Caliper Seizing
Rear Brake Noise and Premature Wear
Mass Airflow (MAF) Sensor Failure
A/C Condenser Leak
EGR Valve and Passage Carbon Buildup
EGR Valve Carbon Buildup and Coolant Leak (SkyActiv 2.5L)
EGR Valve and Passage Carbon Buildup
Battery Pack Capacity Degradation
Concentric Slave Cylinder (CSC) Failure
Coolant Leak from Thermostat Housing (VQ35DE)
A/C Compressor Failure
Cam Tower Oil Leak
Hybrid Battery Pack (HV Battery) Failure
Dashboard Cracking and Melting
Frame Rust and Corrosion
Hybrid Battery Pack Degradation and Failure
6-Speed Automatic Transmission Torque Converter Shudder
KDSS (Kinetic Dynamic Suspension System) Hydraulic Leaks
EGR Cooler Condensation and Engine Intake Carbon Buildup
EGR System Carbon Buildup Causing Rough Idle and Stalling
EGR Cooler Cracking and Coolant Leak
EA888 Plastic Water Pump and Thermostat Housing Failure
EA888 Water Pump and Thermostat Housing Failure
Water Pump/Thermostat Housing Failure
Plastic Water Pump and Thermostat Housing Leak
8-Speed Automatic Transmission Rough Shifting and Shudder
Rear Taillight Seal Water Intrusion
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 for P0401 range from $20 to $15,000, depending on the vehicle and root cause.
Which vehicles are affected by P0401?
Au7o has documented P0401 across 78 vehicle models from 23 manufacturers: BMW, Cadillac, Chrysler, Citroën, Dodge, Ford, GMC, Honda, Hyundai, Jeep, Kia, Land Rover, Mazda, Nissan, Opel, Peugeot, RAM, Skoda, Subaru, Suzuki, Toyota, Volkswagen, Volvo.
Sources (12)
- article6.7L EGR Cooler Failure - PowerStrokeHelp.com
- articleSinister Diesel - 6.7L Powerstroke Most Common Issues
- media3.6L Pentastar V6 Oil Filter Housing Leak Guide - Scotts U-Save
- ForumOil Filter Housing Leak pending repair - Ram Promaster Forum
- ForumOil filter housing under intake manifold cracks leaks - Ram Promaster
- ForumReddit r/MechanicAdvice thread discussing 2012 Mazda3 rear brake caliper seizing
- NHTSANHTSA Vehicle Complaints for 2017 Honda CR-V
- ForumReddit r/MechanicAdvice thread discussing 2017 Honda CR-V CVT judder
- videoHonda CR-V 1.5T CVT Transmission Shudder Repair - EricTheCarGuy
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.