I have a 2009 Mazda 5, automatic. Bought it in September. 6500 miles. Have not had the first oil change yet.

Driving home. Just passed the driveway. Turned around. Suddenly the car was making a really loud screeching sound as we moved forward. Backward, you hear a hissing sound. Again forward, a really loud screeching sound, from near the front of the car. A few neighbors looked outside - it was that loud.

Any ideas what is wrong?

 

is it any louder on full lock?
You may have a drive belt issue, or possibly there is something wrong with the power steering pump. There is an issue with the pipes IIRC.
On a car that new, I would ring the dealer and get it collected

 

What does full lock mean? Is it turning the steering wheel hard all the way to right or left?

Earlier that day, we were parked somewhere and I think the steering was turned all the way. It was really hard to get the key in the ignition to turn. Took some jiggle and pumping the brake.

I'll call the dealer on Monday (closed Sundays).

 

yes, all the way to the left or right.
I wouldn't advise parking with the lock on like that, just for that reason.
The steering pump will usually work harder at full lock and get noiser, so seeming as you said you were turning round, that might have been why you heard something.
Older models had a power steering pipe noise that needed the pipe replacing. Not an issue, just noisy.

 

So what I tried this morning is I backed the car out of the garage. Then I drove forward, turning it hard to the right and hard to left. The noise got softer and softer. Backed up more and tried again, and the noise stopped. I then drove around the block, and the noise was gone. I went to the grocery store, no problem.

I still may call the dealer tomorrow, but I think the turning to lock worked well.

Thanks for your help.

 

I had a similar issue with my Mazda 5 a couple of years ago.
It turned out to be a small stone that had got caught between the brake disc and the metal cover inside the disc on the right front wheel.

 

sounds like an air lock in the power steering system. Check the fluid level and make sure there are no leaks.
I would advise telling your dealer and making sure it is logged as having a problem, and make sure they have it in to check out. The full lock was to diagnose the noise, not cure it, as it shouldn't be there at all.

If the pump has been running dry or any moving parts also, you will have premature wear, and the pump wont be cheap.