NEW YORK — Citigroup announced on Monday that it would replace the head of its consumer banking business — the most troubled part of its financial empire — as the company braces for fresh troubles with home mortgages and credit cards this year.

The executive, Teresa Dial, stepped down after a controversial 18-month tenure, during which she struggled to turn around the division and win the confidence of Citigroup’s chairman and chief executive, Vikram Pandit. Dial, who will stay on as a senior adviser, will be replaced by Manuel Medina-Mora, who runs Citigroup’s consumer banking business in Latin America.

The move comes after federal regulators ordered a comprehensive review of the bank’s leadership. That review, according to people briefed on the situation, gave low marks to Dial and two other members of Pandit’s inner circle: Don Callahan, Citigroup’s administrative chief, and Lewis Kaden, a vice chairman.