The Associated Press reported two more safety probes, affecting Ford and Chrysler.
Federal safety investigators are looking into complaints that the power steering can fail on 83,000 Ford Explorer SUVs from the 2011 model year.
The National Highway Traffic Safety Administration says it has received 15 complaints in which drivers reported that it forced them to use more effort to steer the SUVs. No crashes or injuries have been reported.
In some cases drivers got a warning message before the power steering quit. At times, restarting the SUVs corrected the problem.
The Chrysler probe involves complaints about engine stalling in Chrysler 200 midsize sedans from the 2011 model year that have 3.6-liter V-6 engines.
The National Highway Traffic Safety Administration says it has received 15 complaints that the engines stall without warning while coasting to a stop.
Chrysler spokesman Eric Mayne says the company is working with the government. He says engine performance can be affected by many things, such as software and fuel quality. Mayne says the 3.6-liter engine is in 12 Chrysler models and has traveled millions of miles without problems.