2004 Prius freak out / lights

When warning lights come on, the first and most important thing to do is to get the trouble codes right away, or as close to right away as you can, doing as little as you can that might destroy evidence (like code clearing, certainly; also repeated power cycling, if you can avoid it).

That way, if the codes do go away or get cleared, you'll still know what they were, and you'll have that advantage if they come back.

At this point, they've all been cleared, so about the best information you've got now is what that history code was, if the mechanic told you. (I hope the mechanic told you.)

As you can see, it can be pretty helpful to own something you can read codes with, so you don't have to depend on getting to a shop to find out what your car is saying when warning lights come on.

As a stopgap, you can carry a short wire with you, and use it to retrieve blink codes from the car (you put the wire between the Tc and CG pins at the diagnostic port, and count blinks of the dash lights). You can find other threads here with the details. Not all of the car's systems can give blink codes; some can only be read with a scan tool. But some important ones definitely can, including the brakes. So if you had brake lights on, you at least would have been able to get those codes. And some of the brake system codes can give you a bit of information about things going on elsewhere in the car.

 

There's a pretty good recent thread comparing those. If you get one, you really do want one that can show you all the codes; otherwise, you're less blind, but still partly blind.

 

like any 18 year old computer, there is always the possibility of a glitch. but the triangle just means there's a problem. could it be temporary? possibly, but it may mean that something is going over the edge.
you can't expect a car to last forever. it could be either battery, corrosion, mice, or many other possibilities.

 

hey, 4 dogs in the car? might be worth checking the cooling fan.

agreed, not car buying season

 

Best thing to do when the lights come on is get the trouble codes.

If you didn't, then the second best thing is to just enjoy your life while waiting for the lights to come back, then get the trouble codes.

If you spend the time perseverating about what the possible issues might have been, you could worry about a bunch of unnecessary things. There are hundreds of trouble codes, and some are for scary expensive issues, and many are for pretty easily-resolved ones.