DETROIT >> General Motors Co. said Monday it is recalling 1.5 million vehicles worldwide because the electronic power-steering assist can suddenly stop working, making them harder to steer.

The new recall brings to 6.3 million the number of vehicles GM has recalled since February. The initial recall — now at 2.6 million small cars for an ignition switch defect — prompted the automaker to name a new safety chief and speed up the review of cases that might lead to recalls.

GM said it expects recall-related costs to total $750 million in the first quarter, including $300 million for the ignition switch recall.

Included in the new recall are:

— Chevrolet Malibu from the 2004-2005 model years, plus some 2006, 2008 and 2009 model-year cars.

— Chevrolet Malibu Maxx from the 2004-2005 model years, plus some 2006 model-year cars.

— Chevrolet HHR from the 2009-2010 model years (non-turbocharged only).

— Some Chevrolet Cobalts from the 2010 model year.

— Some Saturn Auras from the 2008-2009 model years.

— Saturn Ion from the 2004-2007 model years.

— Pontiac G6 from the 2005 model year, plus some cars from the 2006, 2008 and 2009 model years.

— Service parts installed into certain vehicles before May 31, 2010, under a previous recall

GM says no deaths related to the defect have been reported. It is still investigating whether there have been any accidents or injuries related to the problem.

GM dealers will replace the power steering motor and other parts for free. Spokesman Alan Adler said owners will be notified of the recall the week of April 28 and will be told when parts are available after that.

The Cobalt and the Ion, which are also involved in the ignition switch recall, share many common parts. GM recalled Cobalts from the 2005-2010 model years for the power steering defect in 2010, but it’s unclear why the company didn’t recall the Ion at the same time.

Federal regulators also opened an investigation into power steering complaints in the Ion in 2010, but didn’t order a recall.