It was the second outage to hit the troubled bank in a week.
The bank said in a statement that "We're experiencing system issues due to a power shutdown at one of our facilities, initiated after smoke was detected following routine maintenance. We're working to restore services as soon as possible."
The stock fell $1.16, or 2.4%, to end the day at $48.06.
Wells Fargo CEO Tim Sloan recently announced that severe restrictions by the Federal Reserve which limit the bank's growth will continue through the end of 2019. The Fed imposed the limits to force the bank to reform its management structure following a series of consumer abuse scandals in recent years.
Sloan has been targeted by U.S. Senator Elizabeth Warren, who called for his removal in a series of tweets last month.
Sloan defended his performance in a recent interview on Jim Cramer's Mad Money.
But Warren remains adamant that the CEO is at the heart of many of the bank's problems.
Wells Fargo is expected to report earnings of $1.11 a share on sales of $21 billion on Apr. 12, based on a FactSet survey of 26 analysts. In the same period a year ago the company posted earnings of $1.12 a share on sales of $21.9 billion.
The stock has fallen about 3% since the company last reported earnings on Jan. 15.