Key Not Accepted - Key will not turn

[aloneinthewoods]

I purchased a 2005 Saab 9-3 Linear a few months back. It came with 2 keys, one never worked, and the other worked like a champ. The car started without issue for a month, a couple of times I would turn the key and the starter would not engage but would start after a redo with no errors on the display. When the temperatures started to drop I started to get “key not accepted". The car would always start on the first try in the morning or after sitting a while, but if I made a short trip and tried to restart it often would not. I would retry with the key warming in my armpit (working on the hunch that the key did not like being cold) and it would always start within 10 minutes or so. Until about a week ago, when it did not start, and would not start. The key would not turn. Had it towed to a shop and they read the following codes:
B3114 remote/wrong code - B3935 malfunction of transponder data - B3060, unknown transponder detected

The first thing I plan to check is the battery to make sure it is providing full power.

Anything else I can do on my own? I am thinking it is a problem with the key is there something I could resolder in there or clean up?

Is the next step to send in my CIM and get a new key at great expense?

[9-3 Aero]

I agree that checking the (main) battery is a good place to start, as a voltage above 11V is required to turn the ignition key from "LOCK" to "OFF".

If yet not done, I would replace the battery of the (until now) working key and synchronize it with the CIM again. I'm aware of that the transponder of the key is a separate part of it, and as such powered by the Ignitition Switch Module (ISM), however it may not hurt to do so.

As the "antenna" of the transponder is a part of the ISM, three of five CIM transponder codes are thrown and 103 other CIM DTCs are not thrown, would I believe the culprit is related to the transponder function as such, and not the CIM specifically. However, if the transponder codes are lost is programming of key(s) / CIM required.

[aloneinthewoods]

Update: After some time messing around with a small specialty shop, the ex-Saab dealer had the car back alive in a few hours. a new CIM and a couple of keys for <1k.