I had my 2001 XC70 parked in the hospital’s garage while my son was being born. On one of my many trips to the car over those 3 days I found a set of keys I had lost and replaced long ago. Since it cost me $300 to replace them, I was happy to have a spare. I wondered if the remote would still work and tried it out. Doors locked just fine!
The day we were sent home I went to the car so I could pull up front and load my wife and son. Car would not start. “Immobilizer. See Manual,” read the message board. I didn’t have a manual with me. I jumped to the conclusion that I had triggered some sort of anti-theft device by using the long lost, disabled remote, so I called my dealer.
“Have it towed to us. We’ll have you back up and running in a couple of days.” This was not an option, so I searched the internet. Lots of questions about this, but no answers and I needed to get my family home. So I’m posting my answer here in hopes that it will get good Google placement and inform the next poor guy who doesn’t have time to have his car towed to the dealership.
I ended up calling a friend for a ride and had the car towed. At the dealership the guy took my keys and locked/unlocked the door 5 times in a row with the remote. This reset the immobilizer and I was on my way. Obviously they couldn’t just tell me that over the phone, but good god. I hope this info can help someone else.