Airbag Light | BMW E46

🚗 2000 BMW 328 (E46)

  • Came in with an airbag light on
  • DTC in Multiple Restraint System (MRS)
    • 20 left side airbag sensor line fault



🩺 Diagnosis

There are only 3 possible causes for this code

  • Left Side Impact Sensor
  • Wiring
  • MRS (airbag) Module


Left Side Airbag Sensor is located under carpet under driver front seat.

Left Side Sensor Location | BMW E46

Left Side Sensor Location | BMW E46


Wiring Check
  • Check for power at pin 3 and ground at pin 1 of the left side impact sensor (S71).
    • If there is no ground at pin 1, check X46 ground under the center console.
      • X46 ground location | BMW E46
    • If there is no power at pin 3, test for continuity from left side impact sensor pin 3 to pin 20 at SRS module (A12).


In my case, wiring was good, but the sensor was corroded from the water intrusion.

Replaced the sensor and all is well.

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