So there I was, typing happily on my Apple Wireless Keyboard and listening to iTunes through my Plantronics 260 headset when, suddenly, the Bluetooth icon in the system menu bar disappeared and was replaced by an error icon. Clicking that icon gave a message, “Bluetooth: not available“. After a bit of Googling I found that [...]

So there I was, typing happily on my Apple Wireless Keyboard and listening to iTunes through my Plantronics 260 headset when, suddenly, the Bluetooth icon in the system menu bar disappeared and was replaced by an error icon. Clicking that icon gave a message, “Bluetooth: not available“.

After a bit of Googling I found that this was an uncommon but reported problem, where apparently the System Management Controller forgets it has a Bluetooth module installed if the CPU temperature rises too high. Odd, and points to a couple of design issues, but fairly easily fixed.

1. Delete Bluetooth preferences (may not be necessary but recommended in a few places)
2. Reset the SMC
3. Install smcFanControl

After resetting the SMC (which involves powering off), Bluetooth came back on like it was never gone.

Hopefully this will help someone else with the same problem!