B1790 airbag control unit fault

What does error code B1790 mean?

Error code B1790 indicates a communication fault in the circuit of the central airbag control unit (Center Airbag Sensor Assembly). This suggests an open circuit or short circuit, which may be caused by defective cables, connectors, or internal electronic components within the control unit itself. As a result, the safety system is usually deactivated.

Technically speaking, DTC (Diagnostic Trouble Code) B1790 describes a malfunction in data transmission between the airbag control unit and its associated sensors or internal components. The control unit continuously performs self-tests to ensure the integrity of the entire SRS (Supplemental Restraint System).

If an irregularity in communication is detected—whether due to a broken cable, corrosion on a connector, or a defect on the main circuit board—the system stores error code B1790. This inevitably triggers the airbag warning light to alert the driver to the issue.

What symptoms indicate B1790?

The primary and unmistakable symptom of error B1790 is a permanently illuminated airbag or SRS warning light on the instrument panel. Often, it is also no longer possible to establish a connection with the airbag control unit using a diagnostic tool, as the communication pathways are disrupted. In this state, the entire airbag system becomes inoperative.

The airbag warning light is the most important visual indicator of a critical fault in the restraint system. It remains lit after the vehicle is started, signaling that the system would not deploy in the event of a crash.

Another typical sign is the complete failure of diagnostic communication. When a workshop attempts to read the fault memory, they often receive feedback that no connection can be established with the airbag control unit, confirming the communication disruption described in the error code.

What causes B1790?

The causes of error code B1790 are varied and typically lie in physical connections or hardware. Common issues include breaks or shorts in wiring, defective connectors due to corrosion, damaged crash or seat‑occupancy sensors, or a faulty coil spring. Internal electronic damage within the control unit itself is also a frequent cause.

A major contributing factor is problems in the wiring harness leading to the airbag control unit. Vibrations, mechanical stress, or rodent bites can cause cables to break or their insulation to degrade, resulting in short circuits.

Connectors are another common weak point. Penetrating moisture can lead to corrosion, interrupting electrical contact. Likewise, pins may loosen or bend due to vibrations.

Peripheral components such as crash sensors in the vehicle’s front and doors, as well as the coil spring on the steering wheel, are also part of the communication network. A defect in any of these parts can disable communication with the control unit entirely.

Last but not least, the fault may originate directly within the airbag control unit. Defective components on the circuit board—triggered by moisture, aging, or voltage spikes—can disrupt internal signal processing and give rise to error B1790.

Which vehicles are affected by B1790?

Error code B1790 occurs across a wide range of manufacturers, particularly among Asian brands like Toyota, Honda, Hyundai, and Daihatsu. European makes such as Opel, Porsche, and Lamborghini can also be affected. At Airbag24, we offer professional repair services for most of these models.

At Airbag24, we repair airbag control units displaying error B1790 for the following models, among others:

Daihatsu: Delta V100

Honda: CR-V (4th generation, RM, 2012–2018), HR-V (3rd generation, from 2021)

Hyundai: i40 (VF, 2011–2019), Staria (US4, from 2021)

Lamborghini: Huracán (LP580-2, 2015–2020)

Mitsubishi: L200 (KL, 2015–2023)

Opel: Crossland B

Porsche: 911 (991 Carrera S)

Subaru: Impreza Sedan

Toyota: Avanza (F650, 2011–2023), Camry (XV10, 1991–1996), C-HR (NGX10, 2017–2023), Granvia (H300, from 2019), GT86 (ZN6, 2012–2020), Harrier (XU80, from 2020), Hilux Revo, Innova (AN40, 2004–2015), Pixis Van, Roomy Custom, Vellfire (H20)

How does repair work at Airbag24?

Professional repair of error B1790 involves targeted refurbishment of the removed airbag control unit. Upon submission, the device undergoes a thorough electronic analysis at Airbag24; defective components on the circuit board are replaced, and cold solder joints are reworked. A final test ensures full functionality, backed by a 12-month warranty.

The process begins with the professional removal of the airbag control unit in your workshop. You then send the defective component for analysis and repair.

At Airbag24, upon receipt of the unit, our technicians perform a detailed component-level diagnosis. They inspect the circuit board for visible damage such as corrosion or burnt-out components and use measurement techniques to evaluate the communication circuits, pinpointing the exact source of the fault.

The refurbishment involves replacing all faulty electronic components, including resistors, capacitors, and integrated circuits. Additionally, conductive traces are repaired, and, if necessary, the software is cleared of stored crash data.

Following successful repair, each control unit undergoes a comprehensive functional test. This ensures the device operates flawlessly again and is ready for immediate installation (plug-and-play). Of course, you receive a 12-month warranty on the completed repair.

Is Repair Worth It for Error B1790?

Repairing the airbag control unit is the most cost-effective solution for error B1790. You can save up to 70% compared to the cost of a new part, which often ranges from 300 to 1,000 euros. Moreover, there’s no need for expensive re-coding, as vehicle-specific data remains intact.

The key advantage lies in substantial cost savings. While manufacturers charge high three- to four-digit sums for a new airbag control unit, repairing the existing one is significantly more affordable.

An additional benefit is preserving the original configuration. A repaired control unit can be installed immediately without requiring time-consuming programming or re-learning by the vehicle at an authorized service center—saving both time and money.

Furthermore, repair represents a sustainable alternative that helps avoid electronic waste and conserves valuable resources. With a 12-month warranty on the repair, you take no risks and receive a reliable, tested solution.