red triangle light coming on - but only at higher speeds (30-40 mph or higher)

As I was driving home a while ago, just a couple of miles from home, the red triangle with the exclamation point inside it came on. I was going 49 mph, and noticed that the warning light turned back off after going under 40 or so. Then when going back above 40 it came on again. It seemed that each time the threshold got a bit lower - as I was driving the last mile on the street where I live, it seemed to come on at about 30 instead of 40.

I had noticed a trail of pink fluid in the garage and driveway earlier in the day, so I checked the ground again and it appears to still be leaking whatever it was leaking (I can't tell for certain, but the pink fluid on the garage/driveway now seems to be fresh, as I'm assuming that the fluid from several hours ago would have dried by now).

Also, this may or may not be related - but I have the oil burning problem that most of these Priuses do after a lot of miles (233,000 in the case of my 2008 Prius), and I had the yellow check engine light come on recently, so I added some oil and the light disappeared after a while (not immediately, it always seems to take a while for some reason). Oddly, the yellow check engine light came back on again, after disappearing, a couple days later... so I added some more oil, just earlier today.

It's getting close to oil change time, so I will go get the oil changed tomorrow morning - just to rule that out as having anything to do with the red triangle light... and also go to O'Reilly to see if they can check the error code, since my mechanic (and all other mechanics) won't be able to look at it until Monday.

I thought I'd report on this just here, just to see if this was a somewhat common problem - like the oil burning problem - that people might be familiar with. Thanks in advance for any input or advice.

 

Yes, I'm aware that the yellow check engine light could mean a variety of things. However, I do know that the car burns oil (have been told by the person changing the oil that there is almost no oil left) - and yes, I am checking the oil before adding any, and it is always very low. The yellow check engine light does go away after adding oil - though not immediately, for whatever reason.

I figured it was probably nothing to do with the oil burning problem, and that it's probably whatever is leaking, but I just wanted to mention it to cover all the possibilities.

I didn't think of it initially (when posting originally), but I seem to recall now that the red triangle has appeared before, many months ago... but after turning the car off it never came back again, until now.

 

Did you not read what I just wrote, in response to the other person?

Of course I'm checking the oil before adding... it's so quick and easy, who wouldn't do that? I didn't explicitly mention it initially because I figured that anyone reading would assume I was checking it, as opposed to assuming I wasn't checking it. Does every expert here think that anyone asking questions here is the equivalent of the person calling for tech support and asks where the "Any" key is?

Sheesh.

And yes, I'm going to take it to the mechanic first thing Monday morning, which I alluded to wanting to do but not being able to because it is a weekend. But of course you're assuming the worst again and you actually think I'm going to drive around carelessly until the car is on fire...

 

I got the oil changed yesterday morning, just to rule that out as having anything to do with the problem (it was getting close to oil change time anyway - almost 5000 miles). The yellow check engine light is still on, constantly, and the red triangle "!" still comes on at higher speeds. The guy at Walmart who changed the oil said the fluid looked like coolant to him, which would make sense since the red triangle seems to come on more often and at lower speeds as the car is left on longer, but we'll see what my mechanic says tomorrow morning.

 

Here's what the reddish fluid looks like. When I felt it, it was not oily or greasy or thick at all - it felt pretty much like water. (There are two streaks only because I don't always park in the exact same place in the garage.)

 

radiator coolant reservoir is empty

inverter reservoir appears full

Yellow check engine light and red triangle no longer coming on now, after adding coolant... until it leaks out again

 

No, I didn't.

After adding the coolant, the coolant quickly leaked back out again and the yellow and red warning lights came back on.

I took it to the mechanic this morning, and he found where the leaks were coming from... It wasn't too bad, thankfully, $128.62 for the part - which the dealer where he went to pick it up at happened to have in stock (apparently a common problem), $100 labor (very honest mechanic, that's why I've been going to him for a couple years now for any problem), $15 miscellaneous tools used in the repair = $243.62

Here's the part that was replaced, just the top part, not the tube which was just transferred to the new part. He didn't even know what to call it, he said it was a water valve or something like that.

The yellow check engine light stayed on after the part was replaced, but after he hooked up the code reader it went away by itself, and now it (and the red triangle) no longer come on, even at high speeds.

 

Yeah, he showed me there were two cracks where the coolant was leaking out.

After getting it replaced, the leaking stopped, but oddly I was still getting the red triangle of death at higher speeds... but much higher speeds compared to before - so it only came on around 70 mph instead of 30-40 mph previously. Also, the heater wasn't working right - something new that didn't happen before the 3-way valve was replaced.

I saw that one of the red triangle of death causes was low oil pressure, and oddly the oil was low even though I had just gotten it changed at Walmart 5 days ago (he told me another person's car he looked at also had low oil after a recent oil change at Walmart - I may have to consider going elsewhere for oil changes in the future), so he added oil, but the problem persisted - both the red triangle and heater.

I did a search while he was working on another vehicle, and one of the possible causes of heater not working was low coolant - but the coolant was no longer leaking and was not low. Then I saw this:

"Sometimes when a thermostat goes bad, it stays stuck open. This allows the coolant to continuously enter the engine. When this happens it'll feel like the heat is barely working or you may notice that it'll work if the vehicle isn't moving but if you get on the highway it stops working."

This seemed to be a similar pattern to how my Prius' heater worked at some times but not other times, so I brought this to his attention, and when he finished with the other vehicle he took out the thermostat to look at it (quite difficult as it was very hard to get to) and indeed it was damaged. He replaced it, and the red triangle of death no longer appears at highway speeds and the heater works all the time now.

Since the thermostat didn't seem to be problematic before recently, I'm wondering if it going bad now has anything to do with the 3-way valve leaking coolant and driving around with low/no coolant for a short time. Anyway, it cost me another $163.34 total - $28.34 for the thermostat, $15 for miscellaneous repair tools, $120 for labor (he only charged me 1.2 hours even though the guideline said 1.8 hours of labor), not terrible, considering I was starting to look online for a replacement used Prius before the 3-way valve replacement, not knowing if the red triangle would be able to be resolved or if it would be too costly to be worth it.

 

The only code I remember was P1116, something to do with the coolant system.