Body, generic

B0031 Second Row Left Frontal Stage 1 Deployment Control

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modeNo

B0031 points to the first firing stage of a frontal airbag that protects the left rear passenger, so it can only be stored where such a bag exists. The known production case is Mercedes-Benz's S-Class of 2020: an optional rear airbag (standard on the Maybach) unfolds from the back of the front seat for the two outer rear seats, built as a gas-filled tube frame that draws ambient air into its cushion. No carmaker publishes B0031 with this meaning. GM used the number differently: the Saab 9-4X 2011 manual groups B0031 with its front seat side airbag codes. Stage 2 and 3 of the same bag follow as B0032 and B0033. The airbag lamp lights and the rear bag may not fire in a frontal crash.

Likely causes

Loose or corroded connector of the airbag lead routed through the front seat backrest
Internal fault in the rear-seat airbag module in the front seatback
Lead stretched or pinched by the seat track or folding mechanism
Restraint module configured for equipment the vehicle does not have (wrong part or coding)

Symptoms

  • Airbag warning lamp on
  • Left rear passenger may lose frontal airbag protection in a crash
  • Safety note: do not probe the airbag circuit yourself; unplug airbag connectors only with the battery disconnected and the stated wait time observed

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–1,200
Time1–4 h

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

Parts involved

second row left frontal airbagsquib circuitsrs seat wiringsrs control module

Related codes

B0032B0033B0039B0030

References: media.mbusa.com, repairerdrivennews.com, patents.google.com, saabwisonline.com.