B1931 code definition
The B1931 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 B1931 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 B1931 code?
In many cases, a B1931 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 B1931 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 B1931 code?
A mechanic can first identify the B1931 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 B1931 code
Body-related trouble codes tend to be specific to certain manufacturers and vehicle makes. A B1931 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 B1931 code?
In the event of a B1931 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 B1931 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 B1931 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 B1931 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 B1931 code?
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This article originally appeared on YourMechanic.com as B1931 OBD-II Trouble Code: Air Bag Crash Sensor 1 Feed/Return Circuit Failure and was authored by Conor Fynes.