235627 - Genuine Volvo - Air Bag Clockspring - P2 -04 DSTC - 8622186

These units go by multiple names depending on who you ask. Steering angle sensor, contact reel, and air bag clockspring are all common names for this part.
When these units fail you'll often get a warning light on the dash stating that DSTC needs service, traction control is off, or something of this nature. Failure should be verified with an OBD reader that can read network fault codes. Replacement is fairly straightforward on this part and involves disconnecting the battery, then the airbag and steering wheel to access the part. Although replacement is a bolt on/ off, components need to be removed in a certain order and orientation or network codes will ensue. Not for the novice mechanic but can be done by an experienced wrench in about 30 minutes. Numerous writeups are available on this replacement online.