Body, generic

B009A Left Side Restraints Sensor 4

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B009A extends the left-side sensor row past the three positions most cars use. No carmaker documents this code publicly. Mitsubishi's airbag index ends the left row at B0093 (C-pillar), and FCA numbers its pillar satellites in its own B276x range, so neither fills the fourth slot. A fourth left sensor makes sense on long bodies or extra seat rows: Bosch says its acceleration satellites can sit on sills, seat cross members, B- and C-pillars and also in the rear, while pressure sensors watch a door cavity. If a vehicle sets B009A, the airbag module has lost a plausible signal from that added satellite or found it shorted, open or wrongly configured; the matching subtype and location must be taken from the maker's own airbag documentation. The airbag lamp comes on.

Likely causes

Damaged line or plug to the fourth left sensor, often after seat or trim removal
Internal fault of the fourth left crash satellite
Airbag module coded for a sensor layout the vehicle does not have

Symptoms

  • Airbag warning lamp on
  • Left side impact detection in the area of the missing sensor is weaker
  • Safety note: airbag system; disconnect the battery and keep the wait time before any work on sensors or wiring, specialist workshop only

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€60–500
Time0.5–3 h

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

Parts involved

left side restraints sensor 4srs wiringsrs control module

Related codes

B009BB009CB0093B009D

References: mitsubishitechinfo.com, bosch-mobility.com, bosch-mobility.com, static.nhtsa.gov.