Dear SJP,

Good p.m. and may this find you well. You read the fault code properly.

I have the exact same car. The sensor unit is under the driver's seat.

I will shortly have the Volvo Technical Manual that deals with these devices, and so be able to address replacing it.

NOTE: BEFORE REMOVING THE SEAT AND/OR TOUCHING THE SENSOR, DISCONNECT THE NEGATIVE BATTERY CLAMP FROM THE BATTERY TERMINAL, AND PUT THE CLAMP IN A PLASTIC BAG. THIS PROTECTS AGAINST AN INADVERTENT TRIGGERING OF AN AIRBAG DEPLOYMENT, AS A RESULT OF THUMPING OR JOSTLING THE SENSOR. AN AIRBAG DEPLOYMENT AT CLOSE QUARTERS CAN BE DANGEROUS AND EXPENSIVE. A NEW AIRBAG UNIT IS ABOUT $1K.

You might be able to get a sensor unit at a salvage yard. I have no idea what they'd charge for it. I'd only take such a unit if it came from a car with "low miles" and which had JUST arrived at the yard. If the car has been sitting out in the open, especially if the doors/windows are open, the sensor likely is ruined. While the seat will protect it from direct rainfall, water accumulating on the floor - or exposure to damp - could damage it pretty quickly.

This is a life-saving part. I'd guess that a new replacement is only to be had from Volvo. It is not likely to be cheap.

I'll be able to tell you more, when I get the Volvo Tech Manual (in a few days).

Hope this helps.

Yours faithfully,

spook.