The National Highway Traffic Safety Administration (NHTSA) is investigating problems of stalling and surging engines on certain Ford and Mercury cars and SUV’s. The investigation will cover Ford Escape and Mercury Mariner SUV’s as well as Ford Fusion and Mercury Milan sedans all from the 2009-2011 model years.

The NHTSA are looking into almost 1,500 consumer complaints about these vehicles going into “limp home mode”. This is when the vehicle’s computer detects an engine problem and limits engine speed to only 20mph. This allows drivers to get their vehicle to safety while still protecting the engine from damage. During a “limp home mode” situation, drivers sometime interpret the limp mode as stalling and increases in power to prevent complete stalling, as surges. Documents posted on the NHTSA’s site on Monday also show that Ford has previously experienced throttle control problems due to a faulty printed circuit boards. A problem Ford says has already been corrected.

The NHTSA say they will start their investigation by looking into the “limp mode home” system. If the investigation does lead to a recall, approximately 725,000 vehicles could be affected.