P1121: owner reports and bulletins
Got P1121 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
13 complaints filed with NHTSA mention P1121, 2 of them since 2015, across 5 different models. The component owners most often filed it under: vehicle speed control.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| TOYOTA TUNDRA | 5 | 2000 |
| TOYOTA PRIUS | 4 | 2006, 2009 |
Manufacturer service bulletins that name P1121
8 technical service bulletins and manufacturer communications filed with NHTSA mention P1121, from 2 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- VOLVO VOLVO, bulletin 10207624: Exhaust Gas Recirculation (EGR) System - Fault Codes SPN 412 FMI 0,2,5; Diagnostic Trouble Codes (DTC) P040A, P040B, P1121 - Temperature Sensor Inspection
- MACK MACK, bulletin 10207662: Exhaust Gas Recirculation (EGR) System - Fault Codes SPN 412 FMI 0,2,5; Diagnostic Trouble Codes (DTC) P040A, P040B, P1121 - Temperature Sensor Inspection
- VOLVO VAH (2013, 2014, 2015, 2016), bulletin 10147500: EGR Fault Codes / Diagnostic Trouble Codes ( DTC's ) SPN 412 FMI 0,2,5, SPN 4752 FMI 7, SPN 2659 FMI 18 / P040A, P040B, P1121, P2457, P0401, P04D9
- MACK PINNACLE (PI/PN) (2018, 2019, 2020, 2007), bulletin 10160169: Diagnostic / Troubleshooting Procedures For EGR System Components; Diagnostic Trouble Codes (DTC) P0401-00, P0402-00, P04DD-00, P1121-00, P1121-98 Or SPN 2659 FMI 16, SPN 2659 FMI 18, SPN 412 FMI 0, SPN 412 FMI 15 - US10…
- MACK ANTHEM (AN) (2017, 2018, 2019, 2020), bulletin 10162587: Exhaust Gas Recirculation (EGR) System - Fault Codes SPN 412 FMI 0,2,5; Diagnostic Trouble Codes (DTC) P040A, P040B, P1121 - Temperature Sensor Inspection
- VOLVO VNX (2013, 2014, 2015, 2016), bulletin 10162677: Exhaust Gas Recirculation (EGR) System - Fault Codes SPN 412 FMI 0,2,5; Diagnostic Trouble Codes (DTC) P040A, P040B, P1121 - Temperature Sensor Inspection
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.