2009 BMW 135i Air Bag Control Module Replacement Cost

A modern car, truck, or SUV is equipped with safety systems designed to protect the vehicle occupants. seat belts are the first and most important line of defense for the driver and passengers in the event of a crash. To supplement the seat belts, a Supplemental Restraint System (SRS) - also known as a passive restraint system or airbag system - is also in place in any vehicle manufactured after 1998. The Supplemental Restraint System may be made up of a series of sensors, as well as the driver's and passenger front airbags, the airbag clock spring (which attaches the driver's airbag to the steering column), front seat-mounted airbags, and roof-mounted curtain airbags (both the seat-mounted and curtain airbags protect occupants in side and roll-over crashes). Seatbelt pretensioners that automatically tighten the seat belts on impact may also be part of the system. The Airbag Control Module (also known as an SRS Control Module or Airbag Electronic Control Unit) is the electronic brain that coordinates all of the components of the Supplemental Restraint System.

The Airbag Control Module constantly monitors data sent from vehicle sensors to detect and evaluate a crash and send a signal to trigger the appropriate Supplemental Restraint System components, such as the airbags, according to the type and severity of the impact. It also determines when the airbags should not deploy in a crash. The Airbag Control Module also stores valuable data (vehicle speed, throttle position, brake usage, seatbelt use, etc.) that can be downloaded and evaluated by a technician.

If there is a problem with the Airbag Control Module, the airbag (SRS) warning light will illuminate on the dashboard. This warning light signals a fault in the Supplemental Restraint System, which could include a problem with a sensor, an airbag, the clock spring, a seatbelt pretensioner, or the Airbag Control Module.