(Updates prices, adds comments)
* Doubts over BOJ's ability to weaken yen strengthen yen
* Traders take profit in dollar gains ahead of Fed meeting
* Commodity currencies gain on oil price gains
* BOJ, Fed will both hold policy meetings on Sept 20-21
By Sam Forgione
NEW YORK, Sept 15 (Reuters) - The U.S. dollar reversed earlier gains against the yen on Thursday as traders doubted that the Bank of Japan (BOJ) would be able to weaken the yen with more policy stimulus, while profit-taking and gains in commodity currencies also weighed on the greenback.
The dollar rose against the yen in morning U.S. trading on expectations the BOJ could ramp up its monetary stimulus after reports in recent days that the central bank could turn more accommodative. over the BOJ's ability to weaken the yen through maneuvers such as steepening the bond yield curve, however, quickly overshadowed those expectations. Traders are also awaiting a Federal Reserve policy meeting on Sept. 20-21, the same dates as the BOJ meeting.
"There are legitimate doubts about the extent to which the BOJ can influence the value of the yen, even with additional policy easing," said Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington.
The BOJ shocked markets in January by cutting rates below zero for the first time in an attempt to weaken the yen, but the yen reaction was only temporary, and it has since gained more than 15 percent against the dollar.
The dollar was last down 0.22 percent against the yen at 102.18 yen JPY= after hitting a session high in morning trading of 102.74 yen.
Analysts also said profit-taking from the dollar's minor gains in morning trading in order to neutralize positions ahead of the Fed's policy meeting was weighing on the dollar, while gains in commodity currencies such as the Australian and New Zealand dollars on the back of gains in oil prices were suppressing the greenback.
The Australian dollar AUD=D4 was last up 0.66 percent against the greenback at $0.7515, while the New Zealand dollar NZD=D4 was up 0.44 percent at $0.7313.
"We're obviously setting up next week for the FOMC and the BOJ, and I think there's probably a lot of squaring up of positions," said Boris Schlossberg, managing director of FX strategy at BK Asset Management in New York.
Traders see just a 12 percent chance the Fed would hike rates next week, down from 15 percent on Wednesday, according to CME Group's FedWatch program.
The euro was last down just 0.05 percent against the dollar at $1.1243 EUR= . The dollar index, which measures the greenback against a basket of six major currencies, was last down 0.04 percent at 95.287 .DXY .