B0090
Left Frontal Restraints Sensor.
- Generic
- Body
- Generic code
- Medium severity
How this code is built
- B
- SystemBody
- 0
- Defined bySAE, the same on every car
- 0
- AreaBody area 0
- 90
- FaultThe specific fault in that area
What it means
B0090 is a body code relating to the left frontal restraints sensor, the crash or impact sensor at the front left of the car that tells the airbag control module when a collision is happening. The module has detected a fault in that sensor circuit or its signal, such as an open circuit, short circuit or implausible data. The exact fault wording and sensor location vary by manufacturer and model.
Symptoms
- SRS or airbag warning light on
- Airbag system may be disabled or limited
- Failed pre-MOT or MOT check because of the airbag light
- Seat belt pretensioners may also be disabled
- Intermittent airbag light after bumps or wet weather
Possible causes
- Damaged, corroded or loose wiring or connector at the left front sensorlikely
- Faulty left frontal impact sensorlikely
- Sensor replaced or disturbed after front-end repair, or mounted incorrectly or loosepossible
- Previous collision damage to the sensor, its bracket or the harnesspossible
- Water ingress or corrosion in the front-end loom or connectorspossible
- Fault within the airbag control modulerare
How to diagnose
- Read all stored and pending codes and note any other SRS faults, as they help narrow down the circuit involved
- Check freeze frame or status data to see whether the fault is current, intermittent or historic
- Visually inspect the left front sensor, its mounting, bracket and surrounding bodywork for damage, looseness or signs of previous repair
- Inspect the harness and connector for chafing, corrosion, bent pins, water ingress and poor locking
- Check the sensor is fitted in the correct position and orientation, and is the correct part for the vehicle
- With the battery disconnected and the manufacturer's SRS safety precautions followed, test the circuit resistance and continuity to the control module against the model's specification
- Check the sensor's live data or status in the diagnostic tool, if the vehicle supports it, while gently wiggling the harness
- Clear the code after repair and recheck that it does not return
How to fix
- Repair or replace damaged wiring and clean or replace corroded connectors
- Replace the left frontal impact sensor if it is faulty or has been damaged
- Refit or replace a loose or deformed sensor bracket and tighten to the specified torque
- Fit the correct sensor and ensure it is correctly seated after front-end repairs
- Repair water ingress sources, then dry and treat affected connectors
- Replace or repair the airbag control module only if the sensor and wiring are proven good and the manufacturer's procedure calls for it
Can I keep driving?
Medium severity
The car will usually drive normally, but the airbags may not deploy correctly in a crash, so have it checked soon. Avoid long journeys or carrying passengers until the SRS fault is fixed if you can.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.