B1931 OBD-II Trouble Code: Air Bag Crash Sensor 1 Feed/Return Circuit Failure

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Cost of diagnosing the B1931 code

B1931 is a diagnostic trouble code (DTC) for "Air Bag Crash Sensor 1 Feed/Return Circuit Failure". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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B1921 code definition

The B1921 trouble code indicates that the airbag deployment system’s Sensor 1 has been reported as malfunctioning by the airbag electronic controller unit (ECU).

What the B1921 code means

The airbag's crash sensor serves to gauge the force of impact and determine whether or not the situation warrants deploying the airbag. A successful airbag deployment must be triggered by both the crash sensor and safing sensor. If a circuit failure has been detected in the airbag's crash sensor, it will disable the vehicle's airbag function.

What causes the B1921 code?

In many cases, a B1921 trouble code is caused by a malfunctioning crash sensor. If this is the case, it will need to be replaced. Problematic wiring is another common cause for this issue. In rare cases, the code may be mistakenly reported by a malfunctioning ECU.

What are the symptoms of the B1921 code?

If the crash sensor circuit is malfunctioning, the airbag system won't be activated in the event of a crash. In addition to the practical symptoms, a stored trouble code and illuminated trouble lamp on the dashboard will be present in a purely diagnostic facility.

How does a mechanic diagnose the B1921 code?

A mechanic can first identify the B1921 by reading the computer with an OBD-II code scanner. All wiring between the ECU and sensors should be checked out for signs of corrosion, damage, disconnection or faultiness. The crash sensor itself should be examined and tested in order to see if it is faulty.

Common mistakes when diagnosing the B1921 code

Body-related trouble codes tend to be specific to certain manufacturers and vehicle makes. A B1921 code may describe different issues depending on the vehicle in question. As such, one code description may be addressed instead of another.

How serious is the B1921 code?

In the event of a B1921 trouble code, the airbag should be considered non-operational. Although the vehicle's drivability won't be affected (unless the issue is more far-reaching) the lack of a working airbag system may pose significant concerns with regards to safety.

What repairs can fix the B1921 code?

Any wiring that has been identified as being damaged or faulty should be repaired or replaced accordingly. If any components related to airbag deployment have been cited as malfunctioning, they should be repaired or replaced. If the ECU has been cited as faulty, it should be repaired or reprogrammed. Following repairs to the B1921 code, the vehicle should be retested. If the code does not return, it will verify that the issue has been solved.

Additional comments for consideration regarding the B1921 code

Airbag components are typically found on the passenger's side of the vehicle, behind the kick panel. Check your vehicle user manual for specific instructions on how to access the airbag deployment system.

Need help with a B1921 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6220.

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B1931

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