The EGT operates on a thermocouple principle and therefore needs not outside electrical power. However most fuel and oil pressure and oil temperature gauges do require electrical power. Also things like fuel contents gauges are usually electrical as well as most turn coordinators and pitot heat for IFR aircraft. All pressure instruments would remain available. Naturally all navigation aids, including GPS [unless it's an iPad or iPhone] would not be available. No wonder most IFR pilots consider a complete electrical failure just as big a problem as an engine failure - really scary!!

Thanks Bob! Hopefully I don't ever get an electrical failure when it comes my time to fly IFR or VFR for that matter!