P0401 Code: Meaning, Symptoms, Causes & Fixes
Reviewed by the Wrenchit.ai editorial team · Last reviewed · Editorial standards
Causes ranked by likelihood
| Cause | Likelihood | DIY difficulty |
|---|---|---|
| Carbon-clogged EGR valve — Clean with throttle body cleaner — saves $300+. | Most likely | 3/5 |
| Clogged EGR passages — Requires intake removal on some engines. | Possible | 3/5 |
| Failed EGR valve — If cleaning doesn't fix it, replace. | Less likely | 3/5 |
| Bad DPFE sensor (Ford) — Specific to many Ford vehicles. | Less likely | 3/5 |
Symptoms of P0401
- Rough idle
- Pinging on acceleration
- CEL
How to diagnose P0401
- Confirm the code. Read P0401 with an OBD-II scanner and note the freeze-frame data (speed, temperature, load) recorded when it set.
- Check for companion codes. Look for other stored or pending codes — they often point to one shared root cause.
- Check: Carbon-clogged EGR valve. Clean with throttle body cleaner — saves $300+.
- Check: Bad DPFE sensor (Ford). Specific to many Ford vehicles.
- Check: Failed EGR valve. If cleaning doesn't fix it, replace.
- Check: Clogged EGR passages. Requires intake removal on some engines.
- Clear and verify. After the repair, clear the code and complete a full drive cycle to confirm P0401 does not return.
Can I drive with P0401?
Yes, but expect rough idle and emissions failure.
P0401 by vehicle
- P0401 on the Ford F-150
- P0401 on the Ford Escape
- P0401 on the Ford Explorer
- P0401 on the Ford Focus
- P0401 on the Ford Mustang
- P0401 on the Chevrolet Silverado
- P0401 on the Chevrolet Equinox
- P0401 on the Chevrolet Malibu
- P0401 on the Chevrolet Tahoe
- P0401 on the Chevrolet Traverse
- P0401 on the Chevrolet Cruze
- P0401 on the Toyota Camry
- P0401 on the Toyota Corolla
- P0401 on the Toyota RAV4
- P0401 on the Toyota Highlander
- P0401 on the Toyota Tacoma
- P0401 on the Toyota Prius
- P0401 on the Honda Civic
- P0401 on the Honda Accord
- P0401 on the Honda CR-V
- P0401 on the Honda Pilot
- P0401 on the Honda Odyssey
- P0401 on the Nissan Altima
- P0401 on the Nissan Rogue
- P0401 on the Nissan Sentra
- P0401 on the Jeep Grand Cherokee
- P0401 on the Jeep Wrangler
- P0401 on the Jeep Cherokee
- P0401 on the Hyundai Elantra
- P0401 on the Hyundai Sonata
- P0401 on the Hyundai Santa Fe
- P0401 on the Hyundai Tucson
- P0401 on the Kia Forte
- P0401 on the Kia Sorento
- P0401 on the Kia Sportage
- P0401 on the Kia Telluride
- P0401 on the Kia Optima
- P0401 on the Subaru Outback
- P0401 on the Subaru Forester
- P0401 on the GMC Sierra
- P0401 on the GMC Acadia
- P0401 on the Ram 1500
- P0401 on the Dodge Charger
- P0401 on the Volkswagen Jetta
- P0401 on the Mazda CX-5
- P0401 on the BMW 3 Series
- P0401 on the BMW X5
- P0401 on the Mercedes-Benz C-Class
Frequently asked questions
What does P0401 mean?
P0401 means egr insufficient flow detected. P0401 means your Exhaust Gas Recirculation (EGR) system isn't flowing enough exhaust back into the intake. Carbon buildup in the EGR valve or passages is the most common cause.
Can I drive with code P0401?
Yes, but expect rough idle and emissions failure.
What is the most common cause of P0401?
Carbon-clogged EGR valve — Clean with throttle body cleaner — saves $300+.
What are the symptoms of P0401?
Rough idle, Pinging on acceleration, CEL.
How much does it cost to fix P0401?
A typical shop repair range is $50–$600, depending on which cause it turns out to be. Cheaper causes such as bad dpfe sensor (ford) should be ruled out first.