In May of last year, Ford Motor Company recalled more than 900,000 Ford Escape and Mercury Mariner models for a power steering flaw. Unfortunately, Ford's fix for the problem might not have worked as well as expected, and the National Highway Traffic Safety Administration may launch an investigation of the repair.
The problem is rooted in an electrical flaw in the models' torque sensor, which is linked to the power steering system. That flaw -- described as "a poor signal-to-noise ratio" -- can prevent the power steering control module from reading steering data from the driver, which sends the system into emergency mode. That involves disabling the power steering entirely and reverting to manual steering mode, increasing the difficulty of controlling the vehicle and increasing the possibility of a crash.
Ford's approach to the problem was to check the diagnostic trouble codes associated with the power steering control module. In most cases, a software update for the component was believed to be an adequate fix, though in some instances, the torque sensor and/or the power steering control module were replaced.
For at least one owner, however, the software update didn't resolve the problem. In February, the owner was still having problems with one of the recalled vehicles and contacted NHTSA. The owner had had the vehicle repaired under the recall, but alleged that "the software update itself may in fact cause further issues with the affected vehicle's power steering, causing it to fail, and ultimately requiring replacement of the torque sensor or entire steering column".
NHTSA is in the process of assessing the validity of the owner's complaint, which is classified as a "defect petition". If NHTSA green-lights that petition, the agency will likely launch an investigation of Ford's fix for the problem, beginning with a preliminary evaluation, followed by an engineering analysis (involving lab tests), and potentially growing to a second recall for the Escape and the Mariner. Should that happen, it would affect nearly 741,000 vehicles registered in the U.S.