P0401: owner reports and bulletins

Powertrain (generic, all makes). We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got P0401 on your scanner? Tell the mechanic your year, make, model and any symptoms and you'll get the likely cause and what to check first. Ask about this code.

What owners report to NHTSA

44 complaints filed with NHTSA mention P0401, 29 of them since 2015, across 26 different models. The component owners most often filed it under: engine.

Most-reported models

VehicleComplaintsModel years reported
CHEVROLET VOLT92016, 2017
HONDA ACCORD51996, 1998
VOLKSWAGEN JETTA32010

Manufacturer service bulletins that name P0401

150 technical service bulletins and manufacturer communications filed with NHTSA mention P0401, from 15 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • MACK CHU, bulletin 10201720: Mack Chassis - Field Service Bulletin - FSB 293-027 EGR Mass Flow Rate Low - (SPN 2659 FMI 18 Or P0401)
  • VOLVO VOLVO TRUCK, bulletin 10201738: Volvo Chassis - Field Service Bulletin - FSB 293-027 EGR Mass Flow Rate Low - (SPN 2659 FMI 18 Or P0401)
  • FORD EDGE (2024), bulletin 11006777: Some 2024 Edge and 2023 Nautilus vehicles built on 28-Aug-2023 and through 02-Apr-2024 equipped with a 2.0L EcoBoost engine may experience an illuminated malfunction indicator (MIL) with diagnostic trouble codes (DTCs) P…
  • LINCOLN NAUTILUS (2024), bulletin 11006777: Some 2024 Edge and 2023 Nautilus vehicles built on 28-Aug-2023 and through 02-Apr-2024 equipped with a 2.0L EcoBoost engine may experience an illuminated malfunction indicator (MIL) with diagnostic trouble codes (DTCs) P…
  • NISSAN ROGUE (2023), bulletin 10232676: MIL ON AND DTC P0401 STORED IN THE ECM IF YOU CONFIRM The Malfunction Indicator Lamp (MIL) is ON and DTC P0401 (EGR System) is stored in the ECM. ACTION 1. Inspect the EGR fitting on the intake air duct (Figure 1) for a …
  • MITSUBISHI OUTLANDER SPORT (2019, 2020, 2021, 2022), bulletin 10241921: This Technical Service Bulletin provides instructions to reprogram the ECU with the countermeasure software when the check engine light illuminates with DTC of P0401/ P0400.

Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.