B0090 DTC – Left Front Impact Sensor Circuit Malfunction

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B0090 DTC – Left Front Impact Sensor Circuit Malfunction

The Diagnostic Trouble Code (DTC) B0090 indicates that the Supplemental Restraint System (SRS) has detected a malfunction in the left front impact sensor circuit. The front impact sensor detects frontal collisions and sends crash data to the SRS control module, which determines whether the front airbags should deploy. The sensor location, wiring, and circuit design vary depending on the vehicle manufacturer.

Symptoms

  • Airbag warning light illuminated.
  • Service Airbag message displayed.
  • Front airbag system may be disabled.
  • B0090 stored in the SRS control module.

Possible Causes

  • Faulty left front impact sensor.
  • Open circuit in the sensor wiring.
  • Short circuit to ground or battery voltage.
  • Loose or corroded electrical connector.
  • Damaged wiring harness.
  • Faulty SRS (SDM) control module.

How to Diagnose B0090

  1. Scan the SRS system and record all stored DTCs.
  2. Inspect the left front impact sensor and connector.
  3. Check wiring for corrosion, damage, or loose terminals.
  4. Verify circuit continuity using a digital multimeter.
  5. Replace the impact sensor if wiring tests are normal.
  6. Clear the DTC and confirm that it does not return.

Typical Circuit Diagram

     SRS Control Module
            │
            │
            ▼
 Left Front Impact Sensor
            │
            │
            ▼
     Crash Signal to SDM
            │
            ▼
   Front Airbag Deployment

Repair Cost

  • Wiring repair: $30–120
  • Front impact sensor replacement: $80–250
  • SRS control module replacement: $300–900

Related DTCs

  • B0089
  • B0090
  • B0091
  • B0092

FAQ

Can I drive with DTC B0090?

The vehicle can usually be driven, but the front airbag system may not function properly during a collision. Repairs should be completed as soon as possible.

Can a damaged connector trigger B0090?

Yes. Corroded, loose, or damaged connectors are common causes of this DTC.

Will replacing the impact sensor always fix B0090?

No. The wiring harness and SRS control module should also be inspected before replacing the sensor.

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