B1906 OBD-II Trouble Code: Air Bag Crash Sensor #2 Feed/Return Circuit Short to Ground

diagnostic check engine light

B1906 code definition

The B1906 trouble code notes a circuit malfunction in the #2 airbag crash sensor.

What the B1906 code means

The B1906 code is a standard OBD-II trouble code that detects a circuit error in the #2 airbag crash sensor. The #2 crash sensor is one of any number of crash sensors (different vehicles use different amounts of crash sensors), which detect when the vehicle is experiencing severe impact, so that the airbags can be inflated. The location of the #2 crash sensor varies depending on the automaker. If an abnormal circuit voltage reading is noted by the airbag control module, body control module, or powertrain control module (PCM), then the B1906 code may be stored.

What causes the B1906 code?

The most likely cause of the B1906 code is a damaged electrical component, such as a wire, fuse, connector, or even the #2 airbag crash sensor circuit. However, it is also fairly common for the code to be the result of a defective #2 airbag crash sensor. It is very rare, but not unheard of, for the code to be triggered by a faulty PCM, airbag control module, or body control module.

What are the symptoms of the B1906 code?

The most noticeable symptom of the B1906 trouble code is the check engine soon warning light, which will likely illuminate on the vehicle’s dashboard. It’s also common for the airbag warning light to come on. Most importantly, the B1906 code means that the airbag system is likely inoperable, and the vehicle will be without airbags if an accident occurs.

How does a mechanic diagnose the B1906 code?

The B1906 code will be diagnosed with a standard OBD-II trouble code scanner. A certified technician will use the scanner to view the freeze frame data for the code, and look for additional trouble codes. If multiple trouble codes are present, then they will need to be diagnosed in the order that the scanner displays them in. Next, the technician will reset the codes, restart the vehicle, and see if the B1906 code remains detected. If the code is no longer present, then an accidental detection, or an intermittent error are the likely causes.

If the code remains detected, then the mechanic will visually inspect all of the wires, fuses, and connectors in the airbag crash sensor system, and replace any that are damaged. Next, the circuit will be tested, and then the #2 airbag crash sensor should be checked.

Anytime a component is replaced, the mechanic will again reset the trouble codes, restart the vehicle, and check for the B1906 code. This helps the technician know when the issue is resolved.

Common mistakes when diagnosing the B1906 code

The most commonly made mistake when diagnosing this code comes from a failure to adhere to the OBD-II diagnosis protocol. It is very important that the protocol be followed step by step at all times, as it helps make sure that diagnoses are accurate and thorough.

Airbag crash sensors are often replaced even when they are fully functional, because damaged electrical components were overlooked.

How serious is the B1906 code?

The B1906 trouble code will not keep a car from being drivable, or present any drivability concerns. However, it is likely that the airbag system is inoperable, and thus the vehicle will be without airbags if an accident occurs. Since airbags are a crucial safety feature that can greatly limit driver and passenger damage, and prevent fatalities, vehicles with this code should not be driven until an inspection has been performed.

What repairs can fix the B1906 code?

Some repairs for the B1906 code include:

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

Additional comments for consideration regarding the B1906 code

The B1906 code is a manufacturer specific trouble code, which means that it has different definitions depending on the automaker. This code signals a #2 airbag crash sensor circuit failure in many vehicles, but can detect an entirely different problem in other cars. Technicians should always pay attention to the make and model of the vehicle they are inspecting when diagnosing this code.

Need help with a B1906 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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