B1902 OBD-II Trouble Code: Air Bag Crash Sensor #1 Ground Circuit Failure

diagnostic check engine light

B1902 code definition

The B1902 trouble code notes an electrical malfunction from the airbag crash sensor #1 circuit.

What the B1902 code means

The B1902 code is a generic OBD-II trouble code that detects a problem with the airbag crash sensor #1 circuit. The airbag crash sensor is used to detect when the vehicle is in a collision, so that the airbags can be deployed. Different vehicles have a different number of crash sensors throughout the car, so the location of the #1 sensor varies from model to model. If at any point an abnormal voltage reading from the crash sensor circuit is detected by the airbag control module, body control module, or powertrain control module (PCM), then the B1902 trouble code may be triggered.

What causes the B1902 code?

The B1902 code is usually caused by one of two things: either damaged electrical components (wires, fuses, connectors, and circuits), or a faulty #1 airbag crash sensor. A defective PCM, body control module, or airbag control module can also cause the B1902 code to be stored, though this is very rare.

What are the symptoms of the B1902 code?

When the B1902 trouble code is detected, the check engine soon warning light will likely illuminate on the gauge cluster, and the airbag warning light may do the same. The airbag system will likely not function, meaning that the vehicle will not have airbags should an accident occur.

How does a mechanic diagnose the B1902 code?

The B1902 code will be diagnosed with an OBD-II trouble code scanner. A trustworthy technician will view the freeze frame data on the scanner and assess the B1902 code, while also checking to see if any additional trouble codes have been detected. If there are numerous codes present, they will need to be inspected in the order in which the scanner displays them. Next, the trouble codes will be reset, and the vehicle restarted, so the technician can see if the B1902 code remains stored. If it no longer does, then an intermittent error, or an incorrect detection are likely to blame.

If the B1902 code remains, then the technician will begin with a visual inspection of the electrical components in the system. Any wires that are shorted, connectors that are open or corroded, or fuses that are blown will need to be replaced. The circuit will then need to be tested, and then the airbag crash sensor should be inspected.

Any time a component is repaired or replaced, the mechanic will reset the codes, restart the vehicle, and again check for the B1902 code. By doing this, the technician will be alerted as soon as the issue has been resolved.

Common mistakes when diagnosing the B1902 code

The most commonly made error when diagnosing this code comes from not complying with the OBD-II trouble code diagnosis protocol. It is imperative that mechanics abide by the protocol at all times, to make sure that diagnoses are efficient and repairs are accurate.

Often, fully functional airbag crash sensors are condemned because electrical errors are overlooked.

How serious is the B1902 code?

A vehicle with a B1902 trouble code will still be completely drivable. However, the airbags will likely fail to deploy if an accident occurs. Since airbags are vital safety features that can limit damage and save lives, a vehicle with this code should not be driven until an inspection has been performed.

What repairs can fix the B1902 code?

The possible repairs for the B1902 trouble code are:

  • Replacement of fuses, wires, and connectors
  • Replacement of the #1 airbag crash sensor circuit
  • Replacement of the crash sensor
  • In rare cases, replacement of the PCM, body control module, or airbag control module

Additional comments for consideration regarding the B1902 code

The B1902 code is a manufacturer specific trouble code. This means that the code has different definitions depending on the automaker. The B1902 trouble code signals a circuit error in the #1 airbag crash sensor for many cars, but a completely different problem for many other cars. It is very important that technicians pay attention to the vehicle that they are inspecting when diagnosing the B1902 code.

Need help with a B1902 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 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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