Coming back from long distance trip across the US, red Triangle suddenly appeared- panic!, car quickly lost power and I pulled over. Has Prius (2004 w 110K miles) towed to nearest Toyota. I was told I needed new hybrid battery- service was very sure of this due to specific codes. ............I decided I wanted a "second opinion" and called another Toyota dealership. The service guy at Toyota #2 told me to check my 12-volt battery connections, that if they are loose, it can give you a red triangle. Luckily, the battery cable WAS loose. I tightened it, and car seemed fine. I went in and told the technicians and they solemnly warned me that I was mistaken- that the codes clearly showed I needed a new hybrid battery.....& they seriously warned me not to drive car off their lot, as I was putting myself in danger. ............Anyway, drove away- car has been fine since.