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U1121 on the 2023 Chevrolet Suburban

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.

This code is specific to a manufacturer and is not described here. Its meaning is in the manufacturer's service information.

Bulletins for this model year that name U1121
PIT5949C2023-05-15. Service bulletin. This Preliminary information communicates an issue during start up that the following symptoms occur: - Service Safety Restraints System Message - Sunroof Inoperative - Sunshade Lights Inoperative - Dome Lights Inoperative - Power Liftgate Inoperative when using switch in overhead console - DTCs U1121 set in the BCM and B1A7A set in the Restraints Module Dealers are to replace the overhead roof console with a new console that has revised software.
PIT5949B2023-05-15. Service bulletin. This Preliminary information communicates an issue during start up that the following symptoms occur: - Service Safety Restraints System Message - Sunroof Inoperative - Sunshade Lights Inoperative - Dome Lights Inoperative - Power Liftgate Inoperative when using switch in overhead console - DTCs U1121 set in the BCM and B1A7A set in the Restraints Module Engineering is currently working on a fix and in the meantime a customer can cycle the dome light switch on/off to correct the condition during that ignition cycle.
PIT5949A2023-02-13. Service bulletin. This Preliminary information communicates an issue during start up that the following symptoms occur: - Service Safety Restraints System Message - Sunroof Inoperative - Sunshade Lights Inoperative - Dome Lights Inoperative - Power Liftgate Inoperative when using switch in overhead console - DTCs U1121 set in the BCM and B1A7A set in the Restraints Module Engineering is currently working on a fix and in the meantime a customer can cycle the dome light switch on/off to correct the condition during that ignition cycle.
PIT59492022-10-17. Service bulletin. This Preliminary information communicates an issue during start up that the following symptoms occur: - Service Safety Restraints System Message - Sunroof Inoperative - Sunshade Lights Inoperative - Dome Lights Inoperative - Power Liftgate Inoperative when using switch in overhead console - DTCs U1121 set in the BCM and B1A7A set in the Restraints Module Engineering is currently working on a fix and in the meantime a customer can cycle the dome light switch on/off to correct the condition during that ignition cycle.

4 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.