Friday morning I started my 2001 Prius (13k mi), and had the master warning light, the hybrid warning light, and the check engine light all staring me in the face. Rebooted, still on. Shut down, reseated the gas cap and rebooted, warnings were still on. Sh*t! Drove straight over to the Dealer. Made sure no one shut the car off before the Prius tech had a chance to look at it. The code turned out to be P3115: replace the HV-ECU. Kind of glad too. Nothing like getting a free ECU upgrade! Now if I could just talk Bill Gates into the same kind of deal for my PC...