New here I have an 08 prius red red car vsc no check engine no codes--I have replaced 12v battery

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You may need to upgrade your OBD2 code reader with something that is more hybrid compatible.

Many prefer to use a 'mini-vci' cable and a copy of techstream (dealer tech software). and others get by with just a OBD2 bluetooth adapter and an App like Dr Prius. Use this link to pick a decent obd2 adapter : Hybrid battery diagnostic and repair tool for Toyota and Lexus

If you have warning lights on the dash then you will generally have stored OBD2 codes (DTCs), which device are you currently using?

 

Gotta read the error codes and subcodes... Most code readers don't read Prius Sub codes... You can buy a mini-VCI dongle for $25 and run Toyota Techstream on an old windows computer, or you can use Dr. Prius App via bluetooth OBD2 reader. Here's buyer's guide: Hybrid battery diagnostic and repair tool for Toyota and Lexus

 

check engine oil level, check all other fluid levels. check inside the engine bay and under the car for anything off like leaking fluids