PRIUS stopped while going 55mph, CHECK HYRBRID SYSTEM light came on.

Well that sucks, hopefully you'll get a new Hybrid battery after it's all said and done!

 

Or inverter?

 

I suppose there is no arguing a vehicle stopping operation at high speeds is always a dangerous and scary situation.

But isn't the truth that with mechanical or even electronic system failure that risk or reality always exists? I think automakers work hard to minimize this type of thing happening but there is no way to take away the risk of instantaneous failure of many systems. Whether this is a blown tire, or a blown engine....or a Prius that suddenly gives you a Hybrid System Warning.

You're saying "No Warning" but that in part is only because The Prius DID give you warning, but in a rather ordered and precise electronic manner.
If you were driving a regular ICE vehicle and the engine suddenly failed, or a tire suddenly blew, you'd get similar "No Warning" but maybe the rather obvious "assurance" of a major problem-squealing tire, engine smoke, loss of power,- instead of the orderly shutdown and quiet warning light.

No...it's never good if ANY vehicle fails at high speed, but I think this is a risk we all take with any and all vehicles we operate at high speeds. Automakers work very, very hard to minimize the risk of system failures, but they can't totally remove it.

Glad you were able to pull "safely" over to the side of the road. Evidently nobody was hurt.
Hope your problem is minimal and easily solved.
Good Luck.

 

Presumably CARB cert if under 150k miles and NJ purchased.
I agree it is non-acceptable but we've never heard a case like this (or much).
You know but we don't know if maintenance was OK or if a mouse family got to your engine.
We just have a short post.

 

welcome to priuschat!

 

This is my guess too. Similar to previous inverter failures in the past, sudden failure while under load.