B0101 SATURN - Driver-Side EFS Not Okay Message
Faulty Driver-Side Electronic Frontal Sensor (EFS)
Driver-Side Electronic Frontal Sensor (EFS) harness is open or shorted
Driver-Side Electronic Frontal Sensor (EFS) circuit poor electrical connection
Faulty Sensing and Diagnostic Module (SDM)
Air Bag Warning Light ON
B0101 Saturn Description
Electronic Frontal Sensor (EFS), also known as a front end sensor, uses a unidirectional 2-wire circuit. EFS sensor modulates current on the interface to send identification, State Of Health (SOH) and deployment commands to Sensing and Diagnostic Module (SDM). The SDM serves as a power source and ground for EFS. When ignition is turned on and EFS detects power from SDM, EFS responds by performing internal diagnostics and sending identification to SDM. SDM considers identification message to be valid if received within 5 seconds of EFS powering up. EFS continually communicates a status message to SDM. When fault is detected, SDM will attempt to reset EFS twice by removing and applying power. If fault is still present, SDM will set a Diagnostic Trouble Code (DTC).
Precautions for SRS “AIR BAG” and “SEAT BELT PRE-TENSIONER” Service
- Never probe the electrical connectors on air bag, side air curtain modules or seat belts.
- Never disassemble or tamper with safety belt buckle/retractor pretensioners, adaptive load limiting retractors, safety belt inflators, or probe the electrical connectors.
- Do not use electrical test equipment to check SRS circuits unless instructed to in this Service Manual.
- Before servicing the SRS, turn ignition switch OFF, disconnect both battery cables and wait at least 3 minutes. For approximately 3 minutes after the cables are removed,
it is still possible for the air bag and seat belt pre-tensioner to deploy. Therefore, do not work on any SRS connectors or wires until at least 3 minutes have passed.
Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.