B1908 OBD-II Trouble Code: Air Bag Crash Sensor #2 Ground Circuit Short to Battery

diagnostic check engine light

B1908 code definition

The B1908 trouble code notes an error from the #2 airbag crash sensor circuit.

What the B1908 code means

The B1908 code is a standard OBD-II trouble code that detects a circuit issue in the #2 airbag crash sensor. The vehicle relies on crash sensors (different makes and models employ a different number of sensors), which detect when the vehicle is in a collision, so that the airbags will be triggered. Because different automakers use different airbag strategies, the location of the #2 crash sensor varies depending on the car. If an abnormal voltage reading from the #2 airbag crash sensor circuit is detected by the airbag control module, body control module, or powertrain control module (PCM), then the B1908 trouble code is likely to be triggered.

What causes the B1908 code?

The most common cause of the B1908 code is damaged electrical components, such as an open circuit, shorted wires, corroded connectors, or blown fuses. Another frequent culprit is a malfunctioning #2 airbag crash sensor. It is also possible for the code to be the result of a defective PCM, airbag control module, or body control module, though controller failure is very uncommonly associated with this code.

What are the symptoms of the B1908 code?

The B1908 trouble code will likely trigger the check engine soon warning light on the instrument panel, and possibly the airbag warning light. It is also likely that the airbag system will not work, meaning the car will be without airbags if there is a crash.

How does a mechanic diagnose the B1908 code?

The B1908 trouble code will be diagnosed using a standard OBD-II trouble code scanner. A trustworthy mechanic can assess the code by viewing the freeze frame data from the scanner. The technician will also use the scanner to check for additional trouble codes, which will need to be diagnosed in the order that they appear in. The trouble codes should then be reset, and the vehicle restarted, so the mechanic can see if the B1908 code remains detected. If the code is no longer present, then an intermittent error or an accidental detection should be suspected.

If the code is still detected, then a careful visual inspection of the wires, fuses, and connectors in the airbag crash sensor system should be performed. The #2 airbag crash sensor circuit will then require testing, followed by an inspection of the airbag crash sensor itself.

After the mechanic replaces any components, the codes should again be reset, the vehicle restarted, and the B1908 once more checked for. This helps the mechanic know when the problem is fully fixed.

Common mistakes when diagnosing the B1908 code

The most commonly made error when diagnosing the B1908 code comes from not following the OBD-II trouble code diagnosis protocol. It’s important that technicians always stick to the protocol when performing diagnoses, as it increases the chances of a successful and efficient inspection and repair.

Airbag crash sensors that are fully functional are often inaccurately condemned because the electrical components in the system were not inspected.

How serious is the B1908 code?

A vehicle with the B1908 code will not have any drivability problems, but the airbags will probably fail to inflate if the car is involved in an accident. Airbags are crucial safety components that can limit damage to the driver and passengers, and often save lives. A car with this trouble code should not be driven until an inspection has taken place.

What repairs can fix the B1908 code?

Repairs for the B1908 trouble code are:

  • Replacement of wires, connectors, or fuses
  • Replacement of the #2 airbag crash sensor circuit
  • Replacement of the #2 airbag crash sensor
  • In rare cases, replacement of the airbag control module, body control module, or PCM

Additional comments for consideration regarding the B1908 code

The P1908 trouble code is a manufacturer specific code, which means that the meaning varies depending on the manufacturer. This code represents a #2 airbag crash sensor circuit malfunction in many cars, but may detect an entirely different problem in other cars. It is important for the technician to always pay attention to the car being inspected when diagnosing the P1908 code.

Need help with a B1908 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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