B0115 airbag control unit fault

What does error code B0115 mean in the airbag control unit?

Error code B0115 indicates a critical open circuit or short circuit in the ignition circuit of the right-side airbag. During its self-diagnosis, the airbag control unit (SRS) detects this electrical fault and deactivates the affected airbag to prevent unintended deployment. The cause is typically a hardware defect in the wiring, connectors, or the control unit itself.

Technically speaking, the system registers a resistance value that falls outside the defined nominal range. In an open circuit, the resistance is infinitely high, whereas in a short circuit it approaches zero. The expected resistance for an intact ignition circuit typically ranges from 2 to 4 ohms.

Once this fault is detected, the control unit stores code B0115 and illuminates the airbag warning light on the instrument panel. This is a direct safety measure, as the protective function of the right-side airbag can no longer be guaranteed.

How do you recognize error code B0115?

The main symptom of error code B0115 is a continuously illuminated or flashing airbag warning light on the dashboard. Additionally, the right-side airbag is completely deactivated, posing a significant safety risk in the event of a side impact. The fault is also permanently stored in the SRS module’s fault memory.

The airbag warning light is the most obvious indicator for the driver. It does not extinguish after starting the vehicle, signaling that all or part of the restraint system is inoperative.

In the event of a crash, the right-side airbag will not deploy if error code B0115 is active. Consequently, the vehicle no longer provides the full occupant protection specified by the manufacturer.

What causes B0115?

The most common cause of error code B0115 is a physical break or defect in the electrical connection to the right-side airbag. This can result from damaged cables, corroded connectors, or a faulty airbag igniter. Less frequently, the issue lies in an internal hardware defect within the airbag control unit itself.

A detailed inspection of the wiring is the first diagnostic step. Often, wires near the doors or under the seat are pinched, broken, or frayed. Loose or moisture‑corroded connectors are also frequent sources of failure.

The airbag sensor or the igniter itself may also fail, reporting an incorrect resistance value to the control unit. This requires professional measurement and testing of the component.

Finally, the airbag control unit itself can be at fault. Internal components such as resistors, capacitors, or ICs may fail due to aging, voltage spikes, or moisture damage, thereby triggering error code B0115.

In which models does error code B0115 occur frequently?

Error code B0115 occurs across brands but is particularly well‑known in certain models from Audi, Jaguar, and Toyota. Vehicles with similar airbag system architectures are often affected. At Airbag24, we have already successfully repaired this fault in numerous vehicles.

At Airbag24, we repair error code B0115 for the following models, among others:

Audi: A4 B7 8E (model years 2004–2008)

Jaguar: XE S X760

Toyota: Kluger Hybrid

This fault may also appear in other models from the VAG group (Volkswagen, Seat, Skoda) that use a comparable control unit platform.

How is error code B0115 professionally repaired?

Professional repair of error code B0115 begins with a systematic diagnosis to precisely locate the source of the fault. If the control unit is the culprit, Airbag24 performs component‑level repairs, replacing defective electronic parts, thoroughly testing the device, and then resealing it. We provide 2 years' statutory liability for defects on every repair.

First, a specialized workshop must inspect the external wiring, connectors, and the side‑airbag igniter. Only when these components are deemed faultless does repairing the control unit make sense.

After sending the removed unit to Airbag24, an initial analysis is conducted using specialized testing equipment. Our technicians open the control unit and identify defective components on the circuit board. Damaged parts such as resistors, capacitors, or integrated circuits (ICs) are carefully desoldered and replaced with new, high‑quality spare parts.

Following repair, the control unit undergoes a comprehensive functional test, during which all safety‑relevant parameters are verified. Only after successful completion is the unit returned to you, ready for “plug-and-play” installation in your vehicle. A subsequent clearing of the fault memory is required.