"The test will be very strict, perhaps too strict," Nowotny told the daily Sueddeutsche Zeitung.
"My fear is that the ECB, keen to do a very good job, will go beyond what has been done in the United States. That could lead to exaggerations," said Nowotny, who sits on the ECB's governing council.
The ECB is scheduled to take over as Europe's banking supervisory authority in November.
Before it does so, it is conducting an audit of banks' balance sheets and, in conjunction with the European Banking Authority (EBA), is it also subjecting the banks to so-called stress tests.
Asked whether he was concerned that one of Austria's banks might fail the test, Nowotny replied: "No. I don't see any wobbly candidates."