What's the Volvo code sa 24 dtc p105421?

Code p105421 in a Volvo means that there is a problem with the camshaft sensor. The sensor is responsible for making sure the cams are in time with the engine. If they are not then the engine will not produce enough power and may even stall out. The sensor is easy to find, being on the manifold, and will simply screw out. If You need to replace it then You can expect to spend about 20 to 30 dollars on a new one. If You ignore this and let the cams operate incorrectly then You will find that over time the engine could sustain damage. This will turn a cheap and easy repair into an expensive and tedious one, so don't sleep on a bad sensor.