Polestar 1 1st generation airbag control unit repair

What is a Polestar 1 1st generation airbag control unit?

As the central control unit of the restraint system (SRS), the airbag control unit in the Polestar 1 1st generation evaluates the signals from the crash sensors, decides within milliseconds in an accident whether to deploy airbags and seatbelt pretensioners, and reports faults via the airbag warning light. After an accident it stores crash data and locks itself.

Without this unit, airbags and seatbelt pretensioners would not know when to deploy. It processes what the sensors report and, in an emergency, enables the appropriate firing circuits. It is installed in the Polestar 1 1st generation (2020 to 2022).

The control unit also stays active during normal driving. It continuously monitors the sensors, the firing circuits of airbags and seatbelt pretensioners, and the wiring in between. If it notices anything, it saves an entry in the fault memory and switches on the airbag warning light.

Why is the Polestar 1 1st generation airbag control unit defective?

Most often the cause is crash data stored in the unit after an accident, even if no airbag has deployed. Ageing electronic components, cold solder joints, moisture and corrosion at the connectors, or voltage spikes, for example from a weak battery or jump-starting, may also be to blame.

Stored crash data cannot be removed with an ordinary diagnostic tool. The unit keeps reporting the fault, even if everything on the vehicle itself has long been in order again.

How can you recognise the problem? Usually the airbag warning light stays on permanently, the fault memory cannot be reset, or the diagnostic tool cannot establish a connection to the control unit.

Common error codes for Polestar 1 1st generation airbag control unit repair

The error codes reveal in which part of the restraint system the fault occurs. In this vehicle they concern the data exchange with the control unit and the chain that carries the firing signal to the airbags.

For the Polestar 1 1st generation, the following codes are reported most often. The first points to lost communication, the second to an interruption in the deployment path:

• U0151 → Communication with the airbag control unit lost
• B15381B → Interruption in the restraint system firing chain

Error codes are read out with a diagnostic tool. A single code does not yet prove, however, that the control unit is defective, as connectors, wiring or an airbag module may just as well be the cause. Only the inspection shows where the fault really lies.

What part numbers are available for the Polestar 1 1st generation airbag control unit repair?

You will find the part number on the label of the control unit; it defines its exact version. Depending on equipment and year of manufacture, the numbers within a model series differ, so you should read the number off the label.

Note down the number from your unit and enter it when you create the repair order. This lets us assign the version unambiguously. Whether the unit is actually defective, however, only becomes clear from reading out the fault memory or from the inspection.

The route to repair follows a clear sequence. It starts with reading out the fault memory at a workshop. Once that is done, you disconnect the battery from the vehicle electrical system and remove the control unit. Then you create the repair order online, and finally you send the unit to Airbag24. Inspecting, repairing and testing usually take us 3–4 working days.

The repaired control unit comes back with all vehicle data and is ready for use as soon as it is refitted — no coding or programming is required.