B1901 - FAULT CODE - OBD2

B1901 Code failures by brands

B1901 LEXUS, TOYOTA, SCION: OPEN IN FRONT DRIVER SIDE PRETENSIONER SQUIB CIRCUIT

Description of DTC code B1901

The driver-side pretensioner circuit is comprised of the left front outboard seat belt (LH) and the center airbag sensor assembly. The function of this circuit is to give instruction to the SRS (Supplemental Restraint System) to work once the deployment conditions are met.

When the B1901 OBD2 fault code is set, it is because there is a malfunction of the driver's side pretensioner circuit, which is caused by an open circuit.

Symptoms of fault code B1901

Check Engine light ON.
Airbag malfunction light illuminated.

Causes of OBD2 B1901

The OBDII diagnostic code B1901 is stored by the following reasons:

The left front (LH) outboard seat outboard belt circuit wiring may have damage.
The left front outboard left seat belt (LH) circuit connections may be faulty.
The left front outboard seat belt (LH) or driver's side pretensioner may be defective.
The center airbag sensor assembly may be damaged.

Possible solutions of the DTC code B1901

To troubleshoot the DTC B1901 OBD2, try this:

Consult the Technical Service Bulletins.
Check that there is no damage to the wires of the driver's side pretensioner circuit. Look for shortages due to corrosion or burns. Repair if necessary.
Use the right tools to verify the right performance of the left front seat outboard belt circuit. Compare actual voltages with those specified in the service manual and if the damage is detected, make adjustments as necessary.
Check the condition of the center airbag sensor and the driver's side pretensioner. If you determine that one of these is damaged, make corrections.