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B1912 OBD-II Trouble Code: Air Bag Diagnostic Monitor Ground Circuit Short to Ground

diagnostic check engine light

B1912 code definition

The B1912 trouble code detects a circuit malfunction from the airbag diagnostic monitor.

What the B1912 code means

The B1912 code is a standard OBD-II trouble code that notes an airbag diagnostic monitor circuit issue. The airbag diagnostic monitor, which is often referred to as the airbag control module, is responsible for receiving input data from the airbag crash sensors if the car is experiencing extreme contact. The diagnostic monitor then relays that information to the airbags, so that they may be deployed. The airbag diagnostic monitor also monitors the entire airbag system upon vehicle startup, to make sure that the system is functioning and communicating properly. If an abnormal reading from the airbag diagnostic monitor circuit is noticed by the body control module or the powertrain control module (PCM), then the B1912 trouble code may be stored.

What causes the B1912 code?

The most common cause of the B1912 trouble code is an electrical component failure in the airbag diagnostic monitor system, or the airbag deployment system. This occurs when a fuse is blown, a connector is open or corroded, or a wire or circuit is short. Another common reason for the code is a malfunctioning airbag diagnostic monitor. The code can also be triggered by an airbag diagnostic monitor that is in need of reprogramming, though this is less likely.

What are the symptoms of the B1912 code?

When the B1912 trouble code is detected, the check engine soon Warning Light and airbag Warning Light will likely illuminate on the gauge cluster, with the airbag light possibly flashing. In most cases, the airbag system will not properly work, so the car will be without airbags if an accident occurs.

How does a mechanic diagnose the B1912 code?

The B1912 code will be diagnosed with the help of a standard OBD-II trouble code scanner. A trained technician will view the freeze frame data from the scanner to assess the code, and to see if there are additional trouble codes present. If the mechanic finds numerous codes detected, then they should be diagnosed in the order that the scanner displays them in. The trouble codes will then be reset, the vehicle restarted, and the code checked for by the technician. If the code is no longer present then an intermittent error should be suspected, or possibly in incorrect detection.

If the B1912 code remains detected, then the electrical components in the airbag system will need to be visually inspected. Any damaged or defective electrical parts in the diagnostic monitor or airbag deployment system should be replaced. Next, the airbag diagnostic monitor itself will be closely inspected. The diagnostic monitor contains an internal thermal fuse that blows not due to resistance issues, but when a short is detected elsewhere in the airbag system. By having the internal thermal fuse blow, the airbag diagnostic monitor helps assure that there will be no accidental spontaneous airbag deployment. However, the internal thermal fuse cannot be replaced, so if it is blown, the entire diagnostic monitor will need to be replaced, along with the electrical issue that caused the problem.

When any components are replaced, the diagnosis should be paused so the trouble codes can be reset, the vehicle restarted, and the code again checked for. By doing this, the technician will be alerted when the issue is resolved.

Common mistakes when diagnosing the B1912 code

The most common mistake when diagnosing this code comes from not properly following the OBD-II diagnosis protocol. Mechanics should follow the protocol at all times, as it greatly increases the chances of an efficient diagnosis, and an accurate repair.

It is fairly common for the airbag diagnostic monitor to be replaced, without a present electrical issue being addressed. If the internal thermal fuse in the diagnostic monitor is blown, then the accompanying short will need to be fixed, or else the replacement diagnostic monitor will quickly fail as well, resulting in a second replacement.

How serious is the B1912 code?

A vehicle with a detected B1912 trouble code will have no drivability problems, but the airbag system will likely be inoperable. Airbags are one of the most important safety features in a vehicle, and they can potentially save the lives of the driver and any passengers. Because of this, the car should not be driven until a diagnosis and repair have taken place.

What repairs can fix the B1912 code?

Repairs for the B1912 trouble code include:

Additional comments for consideration regarding the B1912 code

The B1912 trouble code is a manufacturer specific trouble code. This means that the code carries different definitions depending on the vehicle. While the B1912 code detects an airbag diagnostic monitor circuit malfunction in many cars, it suggests an entirely different issue in other vehicles. Mechanics should always take into consideration the vehicle they are inspecting when diagnosing this trouble code.

After any airbag deployment, the airbag diagnostic monitor will need to be replaced or reprogrammed.

Need help with a B1912 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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