Airbags

B0091 — Left Side Restraints Sensor Circuit Fault

Severity: medium Safe to drive

What B0091 means

The SRS control module constantly monitors its crash and restraint sensors, including the left side one. B0091 is set when the signal or resistance in that sensor circuit is out of range, such as an open, a short to ground or power, or a poor connection. The module can no longer trust the circuit and may disable part of the airbag or pretensioner system.

Symptoms

  • Airbag/SRS warning light is on or flashing
  • SRS is partly or fully disabled
  • Light may go out and come back
  • Code appears after interior work, seat removal or a minor collision

Possible causes

  1. Faulty left side crash or restraint sensor
  2. Open, shorted or damaged wiring or connector in the sensor circuit
  3. Corrosion or poor contact at connectors
  4. Damaged harness in the left door or pillar
  5. Sensor damaged in a minor impact
  6. Internal fault in the SRS module

How to diagnose

  1. Scan all modules with an SRS-capable tool, record the data and look for other SRS codes
  2. Inspect the left side of the cabin: connectors under the seat, in the pillar and door, and signs of past repairs or collisions
  3. Check connectors for corrosion, moisture, bent pins and unlatched locks
  4. Disconnect the battery and wait as the manufacturer specifies, then test circuit resistance and shorts to ground and power
  5. Check the harness for breaks, especially where it flexes at the door
  6. Compare sensor data to the right side if available
  7. Try a known good sensor and recheck
  8. If the circuit is good, test the SRS module

Common fixes

  • Repair the wiring or replace the damaged connector
  • Replace the left side sensor
  • Replace or reprogram the SRS module
  • Clear the code and confirm the light stays off

Questions and answers

What does B0091 mean?

The SRS module detected a fault in the left side restraints sensor circuit. The cause may be the sensor, wiring, a connector or, less often, the module.

Can I drive with B0091?

Yes, the car will run, but crash protection may be reduced. Have it checked as soon as you can.

Can I just clear the code?

Clearing it may turn the light off briefly, but a real fault will bring it back. Find the cause first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.