I just did an AHT because for the last month or so, the fans on my Late 2008 15" MacBook Pro have been going full speed, my battery died a while ago, before the fans became so noisy, and I think this error message has something to do with it. In Energy Saver Preferences, it is set to Higher Performance, I have tried the Better Battery Life setting and the fans go quiet for a while, but then are back to the same RPM as soon as any apps that are CPU hungry start up. There is not really anything unusual showing in Activity Monitor in terms of CPU usage, apart from the kernel_task which consistently uses around 66 threads, (not sure if that's relevant or not.) From what I have read on other discussions about this error code, it seems that a heat sensor is failing because of the dead battery, and is therefore causing the excessive heat and noisy fans, and therefore the sluggish performance of the machine. I have been putting off buying a new battery for some time, but I may just have to bite the bullet. My question is, is a new battery likely to fix the issue of the high fan RPM/heat/sluggish performance?