Senator Sherrod Brown, an Ohio Democrat, also questioned whether Mr. Sloan had done enough to change the culture of Wells Fargo. Since the existence of fake accounts was revealed just over a year ago, other scandals have been uncovered, including instances in which auto insurance customers were charged excess fees and active duty service members had their cars seized.

“The changes Mr. Sloan and his team have made are not sufficient to reform a corporate culture that is willing to abuse its customers and employees in an effort to pad its numbers and increase executive compensation,” Mr. Brown said.

Mr. Sloan defended his actions, both during his decades at the bank before he was named chief executive last year, and during his year as chief executive.

“I am deeply sorry for letting down our customers and team members,” he said. “I apologize for the damage done to all the people who work and bank at this important American institution. When the challenges at Wells Fargo demanded decisive action, the bank’s leaders acted too slowly and too incrementally. That was unacceptable.”

Mr. Sloan said he was still working to fix the bank’s aggressive sales culture.

“I also want to be clear about another thing: Wells Fargo is a better bank today than it was a year ago,” he said. “And next year, Wells Fargo will be a better bank than it is today. That is because we have spent the past year determined to earn back the public’s trust.”