B0021: owner reports and bulletins

Body. We haven't written the explanation for this code yet. Below is what owners and manufacturers have filed with NHTSA.

Got B0021 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

8 complaints filed with NHTSA mention B0021, 7 of them since 2015, across 6 different models. The component owners most often filed it under: air bags.

Manufacturer service bulletins that name B0021

10 technical service bulletins and manufacturer communications filed with NHTSA mention B0021, from 3 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:

  • CHEVROLET BOLT EUV (2022, 2023), bulletin 10232714: This service bulletin provides a procedure to replace the seat pad to correct the condition of Airbag Light On - DTCs B0014 / B0021 SIAB Harness Connector Contacting Seat Back Foam (New Seat Back Foam), Intermittent Serv…
  • CHEVROLET BOLT EV (2022, 2023), bulletin 10237353: This service bulletin provides a procedure to replace the seat pad to correct the condition of Airbag Light On - DTCs B0014 / B0021 SIAB Harness Connector Contacting Seat Back Foam (New Seat Back Foam), Intermittent Serv…
  • CADILLAC XT4 (2019, 2020, 2021, 2022), bulletin 10251360: This technical bulletin provides a procedure to correct the condition of Intermittent Service Airbag System message (DTC B0014 B0021).
  • CHEVROLET IMPALA (2009, 2010), bulletin 10190386: Seatbelt Pretensioner Harness Out of Position, Airbag Indicator Light ON, DTCs Set Some customers may comment that the vehicle airbag indicator light is on. When checking the vehicle for DTCs, the inflatable restraint se…
  • CHEVROLET VOLT (2016), bulletin 10090404: 23010 - SERVICE UPDATE. SOME VEHICLES MAY HAVE BEEN PRODUCED WITH A WELD IN THE SEAT BACK FRAME THAT CREATES A SHARP EDGE THAT CAN DAMAGE THE SEAT SIDE AIRBAG WIRING. THESE VEHICLES MAY EXPERIENCE A LOSS OF CONTINUITY TO…
  • CHEVROLET CAMARO (2016), bulletin 10114993: This Preliminary Information communication provides information to the technician about vehicles that have the airbag warning light intermittently turns on when the wipers are activated. Technician will find a Diagnostic…

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.