Red triangle and 300+ miles from Toyota-capable mechanic

is the battery icon filling up as you downhill?

 

Keep us posted. I’m curious what was the problem.

 

Curious because my 2007 is doing something similar, but only going up hills! No codes. Intermittent Red Triangle of Death. Not every drive. Never when I take her to mechanic!

 

You should check you oil level or coolant level, it probably is very low (to non existent)

 

AFAIK, only low oil pressure, door open (when in drive), or possibly high engine temperature can trigger a master warning light without setting a code.

If there is something else , there should be a "historic" code stored in whatever ecu set it. Not every repair shop has a capable scantool that can talk to all 15-16 ecu's on a Gen2.

There's a sticky thread at the top of the Technical Discussion forum that reviews several OBD apps and devices if you want to be able to scan things yourself.

Posted via the PriusChat mobile app.

 

Thank you. Oil is consistently fine so I will check coolants.

 

maybe a bad door switch

 

Update. Coolant resevoir was full but the coolant level in the radiator was one liter low! I purchased the specific ICE coolant for Gen 2 Prius at Toyota and filled it. My heater that had been blowing cold air now blows hot air. I haven't seen the red triangle light again. Remember that there were no codes for low ICE engine coolant level, just the red thermometer on the main screen when the red triangle popped up. Hope this helps someone.

 

Yes, very good points for a future reader to keep in mind. The car doesn't have any level sensor to give you a code or notice when it's too low. You will only see the overheat warning when that makes things too hot.

And in a Gen 1 or 2, the plastic bottle connected to the radiator is only an overflow tank, a mostly-stagnant backwater that doesn't tell you anything about the actual level in the radiator. You have to look under the radiator cap (only when cold!) to see that.

 

Maybe it doesn't but it SHOULD.
What he reported indicates that the pressure cap wasn't working right.......or that the hose between the filler neck and the bottle was leaking.
A new pressure cap probably is in order.
And inspecting for leaks now that he has it filled.

 

That's the case on enough cars enough of the time that if you have an overflow-bottle system, you should always check your level at the radiator neck. No shortcuts.

If the system is low enough on coolant, and perhaps slurped the bottle empty once, and someone noticed and only topped off the bottle, the underfilled system might not develop enough pressure later to vent out the radiator cap when warm, and therefore might not develop enough negative pressure on cool-down to slurp any more coolant from the bottle. The topped-up bottle will just sit there, next to the underfilled cooling system.

If you have a degas-bottle system like the Gen 3 liftback and v, sure, you can check the level at the bottle.