Airbags

B0090 — Left Front Restraint Sensor Circuit Fault

Severity: medium Safe to drive

What B0090 means

The airbag (SRS) control module detected a problem in the circuit of the left front restraint sensor or a related component. This sensor normally reports frontal impact data so the system can deploy airbags and belt pretensioners at the right moment. When the module cannot trust the circuit, it stores the code and turns on the SRS warning light.

Symptoms

  • Airbag/SRS warning light on
  • Seatbelt warning lamp or chime may activate
  • SRS self-test fails
  • Code returns after being cleared

Possible causes

  1. Failed left front impact/restraint sensor
  2. Damaged wiring or connector in the sensor circuit (open, short, corrosion)
  3. Poor electrical connection or low system voltage
  4. Sensor disturbed by collision, body or suspension repair
  5. Internal SRS control module fault (less likely)

How to diagnose

  1. Scan with a tool that reads SRS codes and note all codes and freeze frame data
  2. Check battery voltage and terminal condition
  3. Inspect the left front sensor connector and wiring for corrosion, damage or a loose fit
  4. Look for signs of past collision damage or a sensor that is loose or incorrectly mounted
  5. Test circuit continuity and resistance per the factory wiring diagram
  6. Clear the code and see if it returns; swap in a known-good sensor if needed
  7. If the circuit is fine, check the SRS module and its connectors

Common fixes

  • Clean and secure the connector terminals
  • Repair or replace the damaged wiring section
  • Replace the left front restraint sensor
  • Replace or reprogram the SRS control module if it is at fault

Questions and answers

What does code B0090 mean?

It indicates a fault in the left front restraint sensor circuit. The SRS module is not getting a valid signal from it, so it lights the warning lamp.

Can I just clear B0090 myself?

You can clear it, but it will return if the cause remains. The SRS light is your only warning that the protection system is compromised, so fix the fault first.

Is it dangerous to drive with this code?

The car will drive normally, but airbags and pretensioners may not work in a crash. Have the system inspected as soon as you can.

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.