Can someone please tell me what this light means

If you are talking about the warning light that looks like this: ((!))
then that is telling you that your brake system is impaired. I am surprised that you have not said that the ABS and VSC warning lights are also on.

I recommend that you drive at moderate speeds and allow plenty of braking distance while you need to run your errands this evening. Then take your car as soon as possible, to your local Toyota dealer so that a diagnosis can be performed. Good luck.

 

If it looks like Do You Know What This Symbol Means?- Yahoo! Autos Article Page, then it's the low tire pressure warning light. IIRC, it's yellow on the 2nd gen. I've seen it on my 06 Prius and sure it enough, it was due to a screw in a tire.

 

The inner set of () in my post #2 is meant to approximate a circle. If you see that symbol then the brake system has a problem.

The ABS and VSC warning lights look like three letters each - no icon.

cwerdna has proposed a reasonable possibility: that the low tire pressure warning light is on. In that case the icon looks like the cross section of a tire.

 

Tracysbeans, since you have said that you don't know much about these things, Tideland's post might need some clarification.

The Toyota recommended pressure is 35 psi in the front tires (or tyres) and 33 psi in the rear, regardless of what the outside temperature is. What Tideland is telling you is that, even if there is no air leakage at all, if you set the tires to the recommended pressure when the tires are warm, the pressure will drop when the temperature drops. You should inflate the tires to whatever pressure you choose when the tires are cool; preferably when they have not been driven on for a few hours. If you can't do that, drive for as short a distance as possible before setting the pressure.

 

Beyond the two most recent posts, many 2nd gen owners here will argue that Toyota's "recommended" pressures in the door jamb are too low and lead to uneven wear (edges wearing out first) instead of uniform wear besides hurting fuel economy. I'd agree w/that argument as I had that w/my Integrities even though I was inflating them slightly beyond recommended pressures.

I'd suggest at least 38 psi front and 36 psi rear.

 

I just purchase a used '08 Prius & after 2 weeks saw that same symbol this morning (first time overnight frost). I figured out it was low tire pressure & checked the tires & didn't see any significant change (suppose to light up when 25% less pressure than baseline). I found out you can reset by holding reset button below the steering column until it flashes slowly 3x (I actually had to read the manual to figure this out).

 

Yes, the overnight temp around here droppedto below freezing.
So my light came on.
Pressure was probably last set when the outside temp was at least 70.

you sometimes have to adjust the temp seasonally.
Heat expands/cold contracts.

Most people naver check the air in their tires when the temp drops.
Prius owners at least have a warning light............

 

The simplest way to preserve fuel economy and tire life is to check and maintain tire pressures monthly. Spend $8 on a digital gauge and do it yourself at home after the car has been sitting for an hour or more.

 

I have a Prius II (2004) so is the 2010 the V? That would make the update in 2006 the III and I guess the 2008 the IV.

So by that rule, in the summer when the temp is 110, I should have 11 psi, and in the winter when it is 38, I should have 3.8 psi.