B1625: Side Airbag Sensor LH Fault

Hardware fault

What B1625 means

Side airbag sensors mount low in the driver side body structure, near the pillar or inside the door area, where they can feel a lateral impact almost as it starts. The ECU relies on that reading to fire the driver seat side airbag and the curtain in time. B1625 says the sensor and its circuit are no longer reporting the way the ECU expects.

The definition names the circuit, so both the sensor and its connections are in scope. Water running down inside a pillar or a door, salt carried in with it, and the shock of thousands of door slams all work against that assembly. Connector corrosion and a dead sensing element look much the same from the driver seat.

Common causes

• A failed sensing element inside the left side airbag sensor
• Water entering the pillar or door area and reaching the sensor or connector
• Corroded connector pins from long term moisture in that location
• Wiring damage where the harness passes the sill, pillar, or door boot
• Impact damage from an earlier side hit or a hard curb strike
• A loose mounting bolt allowing the sensor to shift in its bracket

Crash data or hardware fault?

This code follows the present condition of the sensor and its circuit, not a crash history. The ECU checks it at every key cycle and stores the code again until the fault is corrected. Deployment records are the permanent kind of entry, made when airbags fire, and a module reset is what takes those out.

Does our reset clear it?

Bench service on the module will not restore a sensor circuit. Our mail-in reset addresses stored deployment data, so it applies here only when the vehicle was struck and the ECU is holding a crash record as well. Repair the wiring or replace the sensor first and confirm the lamp stays out, then handle the stored data if there is any.

Which makes throw it

Toyota is the make our lookup lists for B1625. It sits in the same B16 sensor range as the front sensor codes, and the LH marking points you to the driver side of the vehicle.

What to do next

Take the driver side sill or pillar trim off and look for water and corrosion at the sensor connector, since moisture in that area is the most frequent cause. Check the harness where it passes through the door boot if the sensor is door mounted on your vehicle. Confirm the sensor is tight against its bracket and reading clean power and ground. When the sensor has failed, we sell genuine OEM Toyota side impact sensors matched by VIN at 501-988-0611. Related codes: B1620, B1650, B0078.