Sorry for upping an old topic, but....

I just joined this forum to say thank you for James and Wyr for figuring this out... I don't even know if either of you even post here any more.

I have a 2005 Aveo.

For the past couple weeks, I was braking hard the first and maybe second time I had to brake in the morning. Then last week, it didn't stop braking hard.

I googled my symptoms and found out that it was maybe a good chance that it was a check valve issue... but I couldn't find what looked like a common-looking check valve. I think Autozone even had a normal looking check valve listed on their website for sale.

But thanks to this topic.. I found out that the valve was built into the booster hose.. Nobody local had a new one in stock, so I ordered a new one off Amazon, got it the next day, put it on... and whammo... awesome braking again!..