Nissan Motor Co. CEO Hiroto Saikawa resigned from his post Monday after admitting to overpayment of remuneration and his successor, to be picked next month, will face immense pressure to revive profitability and repair ties with alliance partner Renault SA.

Chief Operating Officer Yasuhiro Yamauchi, a 63-year-old longtime Nissan director, has replaced Saikawa, 65, as acting CEO while Nissan's nomination committee led by an outside director is in the process of selecting a permanent successor by the end of October.

The company has been struggling since the arrest of former Chairman Carlos Ghosn last November over alleged financial misconduct, and the successor will be tasked with strengthening ties with Renault to survive in the fast-evolving and fiercely competitive auto industry.