Body, generic

B0200 Air Bag System Voltage Out of Range

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

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.

Likely causes

Weak battery or charging fault letting system voltage sag, often while cranking
Poor ground or loose supply pin at the airbag control unit connector, or a corroded fuse contact
Airbag control unit faulty, for example its internal supply or reserve capacitor

Symptoms

  • 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

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€50–800
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

srs control modulevehicle batterysrs power circuit

Related codes

B00D2B00D3

References: bosch-mobility.com, bosch-semiconductors.com, patents.google.com, patents.google.com.