B0021Left Curtain Deployment Control 1
- Generic OBD-II code · Body
- How the car detects it
- In the J2012 order B0021 is the first firing loop of the left curtain airbag, the bag that drops from the roof rail over the side windows. Mitsubishi files it under the left curtain module and stores byte 11, 12, 13 or a short to another circuit once the condition has lasted 2 seconds. Mercedes-Benz reads B002113 as an open squib of the left window bag on the A-Class, CLA and GLB, where raised contact resistance at the restraint unit plug was the cause (LI54.21-P-070658). Curtain 1 is the only or front curtain inflator; B0022 is the second one. GM Global A modules use B0021 for the passenger seat side airbag instead, with bulletins on seat harness contact (PI1469, 23-NA-030). Airbag lamp on; the left curtain may not fire.
- What you may notice
- Airbag warning lamp on
- Left curtain airbag may not deploy in a side impact or rollover
- Safety note: do not probe the airbag circuit yourself; unplug airbag connectors only with the battery disconnected and the stated wait time observed
- Likely causes
- LikelyRaised contact resistance at the curtain airbag or restraint module connector
- PossibleDamaged lead along the A-, B- or C-pillar or the roof rail
- PossibleInternal fault in the left curtain airbag module
- RareFault or unsuitable software in the restraint control module
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €100 – €1,000
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.