B0200Air Bag System Voltage Out of Range
- Generic OBD-II code · Body
- How the car detects it
- B0200 is not documented in public: no publicly available J2012 list and no carmaker uses it with this meaning. What the title describes is real. An airbag control unit runs from the vehicle battery and needs a stable supply to fire reliably; Bosch rates its commercial vehicle unit for 8.5 to 32 V. An energy reserve capacitor, 2 x 4.2 mF in that unit, keeps it working for a defined autonomy time if the battery is torn off in a crash (Bosch EP1526986B1). Airbag system chips such as Bosch CG903 monitor their supply voltages and test the reserve capacitor all the time. A patent for an airbag ECU (US20140142812A1) logs how long the supply stayed in a set range, for instance during cranking dips. Outside the range the module turns on the airbag lamp, the readiness indicator FMVSS 208 demands.
- What you may notice
- Airbag warning lamp on, sometimes only after a cold start or jump start
- Other modules may also log low-voltage faults
- Safety note: airbags may not deploy while the fault is present; work on the system only with the battery disconnected and the wait time observed
- Likely causes
- LikelyWeak battery or charging fault letting system voltage sag, often while cranking
- PossiblePoor ground or loose supply pin at the airbag control unit connector, or a corroded fuse contact
- RareAirbag control unit faulty, for example its internal supply or reserve capacitor
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €50 – €800
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.