B1570 airbag control unit fault

What does error code B1570 mean in the airbag control unit?

The error code B1570 indicates a specific fault within the airbag system. Typically, it points to a malfunction of the passenger airbag manual cut-off switch, a short circuit in the associated wiring harness, or an internal defect in the airbag control unit itself. The exact cause may vary depending on the vehicle manufacturer.

Technically speaking, the airbag control unit detects an implausible electrical condition in the monitoring circuit of the passenger airbag cut-off switch. This could be a short to ground, an open circuit, or an incorrect resistance value. The system classifies this deviation as safety-critical, activates the airbag warning light, and stores error code B1570 in the fault memory.

In some manufacturers, such as Mitsubishi, code B1570 is directly linked to the passenger airbag cut-off switch. In other brands, for example Fiat, the fault can also be caused by elevated standby currents or interference from adjacent electrical components like the radio, which affect the airbag control unit.

What symptoms indicate error B1570?

The primary and most obvious symptom of error code B1570 is the permanently illuminated airbag warning light on the instrument cluster. This light does not turn off after starting the vehicle, indicating an active, safety-relevant fault in the restraint system. In some cases, warning messages may also appear on the display.

Another sign is the malfunctioning status indicator for the passenger airbag. The lamp that shows whether the airbag is activated or deactivated may not function correctly or displays a persistent error status.

When attempting to clear the fault memory with a standard diagnostic tool, error B1570 often reappears immediately. This is especially true if crash data is stored in the control unit, as such data causes a permanent lockout of the system until a professional electronic repair is performed.

What are the most common causes of error code B1570?

The most frequent causes of B1570 are electrical faults around the passenger airbag cut-off switch, such as damaged cables or connectors. Likewise, stored crash data following an accident or internal hardware defects in the control unit—caused by moisture or voltage fluctuations—can trigger this error code.

A major contributing factor is defective or damaged cables and connectors. Corrosion at the contacts, cable breaks, or pinching, particularly in the wiring harness leading to the cut-off switch or at the coil spring in the steering wheel, can initiate the fault.

Stored crash data is another significant cause. After an accident, the control unit permanently saves this information to prevent reuse. Error B1570 can result from this lockout and cannot be cleared without an electronic reset of the control unit.

Internal defects within the airbag control unit itself can also cause the error. Penetrating moisture may lead to short circuits on the circuit board, while voltage fluctuations or general undervoltage in the vehicle’s electrical system—especially in older units with sensitive electronics—can damage the device.

In which vehicles does error B1570 occur?

Error code B1570 appears across various manufacturers. It is particularly commonly diagnosed in models from Alfa Romeo, Honda, and Mitsubishi. Repair requires specialized knowledge of each brand’s specific control unit architecture.

At Airbag24, we repair error code B1570 for the following specific models and series:

Alfa Romeo: 90 (162)

Honda: Civic 9th Generation (2011–2017)

Mitsubishi: Pajero Sport (QE), Pajero iO (H60)

How is error B1570 repaired?

Professional repair of error B1570 begins with removing the airbag control unit and sending it in for service. At Airbag24, the unit undergoes a thorough electronic analysis to determine the exact cause. Next, crash data is erased, defective components replaced, and the unit tested on test benches. We provide a 12-month warranty on successful repairs.

The process starts after the control unit is removed in a specialized workshop. It is crucial that work on the airbag system is performed only by qualified personnel, as improper handling can be life-threatening.

Upon arrival at Airbag24, the control unit is read using specialized diagnostic software to analyze its internal fault memory. Our technicians inspect the circuit board for visible damage, cold solder joints, or signs of moisture.

The actual repair involves electronically erasing stored crash data and restoring the hardware. Defective components, connectors, or circuit traces are professionally repaired or replaced. Finally, the software is restored to its factory settings.

After the repair, the control unit is tested under real-world conditions on a specialized test bench to ensure full functionality. It is only returned once the test is successful. In some cases, re-encoding the vehicle identification number at a qualified workshop may be required after reinstallation.