Airbag control unit with part number P31264861

What does the airbag control unit P31264861 do?

The airbag control unit P31264861 coordinates the restraint system (SRS) in Volvo vehicles. It analyses the signals from the crash sensors, determines the triggering of airbags and seatbelt pretensioners within milliseconds in an accident, and monitors the system continuously.

If it detects a fault, it displays this via the airbag warning light in the instrument cluster. The verdict in a crash is made by the control unit; the sensors only supply the input data.

After an accident, the unit secures crash data and then locks itself. What lies behind this, and how a failure can be recognised, is explained in the following sections.

Why does the control unit P31264861 fail?

The most common cause for the P31264861 is crash data stored after an accident, even if no airbag has fired. Further causes are ageing components, cold solder joints, moisture and corrosion at plug connections, and voltage spikes.

Crash data remains in the memory. A normal diagnostic tool cannot erase it, which is why the problem cannot be fixed by resetting.

Ageing components and cold solder joints are weak points that can make themselves felt over time. Malfunctions can also occur without any accident.

Moisture and corrosion disturb the contact at plug connections. Voltage spikes, for example from a weak battery or a jump start, put additional strain on the electronics.

How can you tell that the P31264861 is defective?

The airbag warning light in the instrument cluster lights up on the P31264861 either continuously or intermittently. In addition there is an error message in the instrument cluster, no connection to the diagnostic tool, and a fault memory that cannot be cleared.

The warning light is the visible side of the system's self-monitoring. As long as it is lit, airbags and seatbelt pretensioners may possibly not deploy in an emergency.

Even if the diagnostic tool does not communicate with the control unit, a plug or a cable may be the cause. Which area is affected is shown only by the fault memory once it has been read out.

Which vehicles is the P31264861 fitted in?

The control unit P31264861 is fitted in these vehicles: Volvo S80 AS (2006-2016).

The list shows which vehicles are recorded for this number.

• Volvo S80 AS (2006-2016)

Compare the part number on the label of the removed unit with this page; this only tells you whether you have the right unit. Also have the fault memory read out before you plan any further steps. Only this result shows whether the control unit is faulty or whether a plug or cable is the cause.

For the same vehicles, we also repair control units with the part numbers 285001456, 9472627, P30658912.

How does the repair of the P31264861 work?

First have the fault memory of the P31264861 read out and enclose the log. Only then disconnect the battery and remove the unit; afterwards create the repair order online. At Airbag24, testing, repair and function test usually take 3–4 working days.

The order of these steps is not a formality but serves safety when working on the airbag system.

At Airbag24's premises, the unit is checked, repaired where necessary, the crash data is erased and a function test is carried out. The unit then goes back to the sender.

Our repairs come with 2 years' statutory liability for defects. 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.

How does the control unit P31264861 get to Airbag24?

You send the P31264861 to Airbag24 as a parcel, or you book a UPS collection for an extra charge. The return after the repair is made by UPS.

Pack the control unit shock-resistant and enclose the printed repair order.