A second test confirmed that a persistent air leak is caused by a faulty positive pressure relief valve behind the orbiter's toilet, said NASA spokesman Bill Johnson at Kennedy Space Center. The valve is not part of the toilet.
"They positively identified that it is a valve they refer to as valve B," said Johnson.
Preliminary plans are to replace the valve with one now in shuttle Atlantis.
It's a leak in the craper! Jeez Louise!