sometimes my ignition doesn't catch

There can be several things that can cause this and only a thorough analysis of the starting system will pinpoint the exact cause, not what you probably wanted to hear but these are very complex computerized vehicles. However I can offer some ideas as to what you can check and what it might be, but i still recommend having a pro look at it if you don't find an issue. One thing you can check is power to the Starter when the engine doesn't crank over. If you have power to the starter, try smacking it with a hammer when it doesn't work. If it instantly starts working, then be sure the fire terminals are tight and if so, it needs a starter. If you don't have power then it's time to call in a pro. These cars have an ignition key with a transponder in it, and this system that reads the transponder, called the Immobilizer, can have issues. About the only thing you can do to check this is to try another key and see if the problem persists. If it does, then go see a Volvo specialist. Good Luck

As with any concern, without proper inspection we can only theorize. A scan of the vehicle and live data display can go a long way to isolating the cause. Many vehicles require a memory saver to be used when changing a battery to keep settings and preferences and module data in tact. If the memory saver isn't used, then calibrating and resetting some modules may be required. If the no crank no start is happening independent of the battery being swapped, then a diagnostic is recommended. We utilize today's current technology to be able to diagnose and repair today's vehicles. You would be looking at $57.90 to scan your volvo.