2002 S60 with 199,000 miles on it.

I bought the car used about ten years ago and it only came with one key. I didn't want to pay $200 for a key and programming so I found a work around.

I found some key blanks online and had a lock locksmith cut them for me. All told, blanks and cutting was $100

I got another ring antenna at the junkyard and connected it in place of the antenna on the car. I then Zip tied the original key to the connected ring antenna and stuffed under the steering column cover.

All was good. My faux key worked perfectly until just two days ago. I started getting the "Start Prevented" message and it would take two, three, five, six attempts to start. Yesterday evening, after two or three "Start Prevented" messages, the engine would crank but not start. Finally after a few attempts, it started and I got home.

When I was doing the aforementioned work around, I found that if the key wasn't in the exactly right spot on the ring antenna, the engine would crank but not start. You'd think that nothing would happen at all but no.

Bright and early this morning, I was tearing my steering column apart and reconnected the original ring antenna and used the original key. So far, it has started twice. We'll see if that solves it.

So, anyone have experience with imobilizer problems? If it wasn't the antenna, any thoughts on what be causing the issue?