P0401 on the 2012 Toyota PRIUS
The bulletins listed name this code in NHTSA's summary, or are about the same components. A bulletin or a recall listed here may apply to the model year. None of it is a diagnosis.
Nobody has written a description of this code yet.
| ZF3_Toyota POL16 | 2019-09-16. Service bulletin. Warranty Enhancement Program: Toyota has received reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve in some vehicles. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
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| T-SB-0027-16 | 2018-04-23. Service bulletin. TSB: Some Prius, Prius V, and Prius PHV vehciles may exhibit a rough idle or tapping noise from the HV transaxle at cold start. The Check Engine Light may also illuminate with (DTC) P0401 (Exhaust Gas Recirculation Flow Insufficient Detected). Due to excess carbon build-up at the valve assembly, the valve will stick, causing the engine RPM to fluctuate. Follow the procedures in this bulletin to address the condition. |
| T-SB-0027-16 | 2018-04-23. Service bulletin. TSB: Some Prius, Prius V and Prius PHV vehicles may exhibit a vibration due to rough idle and/or tapping noise from the HV transaxle at cold start. The Check Engine Light may also illuminate with (DTC) P0401 (Exhaust Gas Recirculation Flow Insufficient Detected). Due to excess carbon build up at the valve assembly, the valve will stick causing the engine RPM to fluctuate. Follow the procedures in this bulletin to address this condition. |
| ZF3_Warranty Pol | 2018-04-23. Service bulletin. Warranty Policy Bulletin (POL16-04): In these vehicles, Toyota has received some reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
| ZF3_Dealer Lette | 2018-04-23. Service bulletin. Dealer Letter: In these vehicles, Toyota has received some reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
| ZF3_Dealer Lette | 2018-04-23. Service bulletin. Dealer email: In these vehicles, Toyota has received some reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
| ZF3_Region Lette | 2018-04-23. Service bulletin. Region Letter: In these vehicles, Toyota has received some reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
| ZF3_Region Lette | 2018-04-23. Service bulletin. Region email: In these vehicles, Toyota has received some reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
| T-SB-0075-13 | 2018-04-02. Service bulletin. Some 2010-2012 model year Prius vehicles equipped with a 2ZR-FXE engine may exhibit a MIL "ON" condition with Diagnostic Trouble Code P0401 (Exhaust Gas Recirculation Flow insufficient Detected) present. The Exhaust Gas Recirculation Valve has been improved to address this condition. |
| ZF3_Warranty Pol | 2017-08-14. Service bulletin. Warranty Policy Bulletin (POL16-04): Toyota has received reports of a rough idle and/or rattle noise from the transaxle at cold start due to a sticking Exhaust Gas Recirculation (EGR) Valve in some vehicles. If this occurs, the vehicle may illuminate the check engine light and set diagnostic trouble code (DTC) P0401. |
16 on file from NHTSA, as of 2026-10-19. See them in the bulletin list. A bulletin lists model years: read the document for which vehicles it concerns.