Federal safety regulators are stepping up an investigation of the vehicle speed control system in 2004 and 2005 Chevrolet Aveos.
The Office of Defect Investigations (ODI) which is part of the National Highway traffic Safety Administration (NHTSA) has upgraded its evaluation of complaints which began October 19, 2007 about stuck throttles in the Aveo because of ice formation within the engine air intact tract.
The change, according to ODI, follows a safety recall by General Motors involving substantially similar vehicles manufactured for sale in Canada.
GM, according to the federal safety group twice revised the Canadian recall to include more substantial changes to the throttle body, intake manifold, positive crankcase ventilation and engine cooling systems to further reduce air intake tract.
After receiving 28 complaints of a stuck throttle in vehicles in the U.S. along with 46 warranty claims affecting 63 vehicles, investigators suspect the defect occurs in the winter when the temperature is below freezing.
Information provided to ODI by GM does not include events involving stuck throttles during the most recent winter months so the investigation will be intensified to further study the frequency of the alleged defect, according to ODI.
An engineering analysis is often the last step before a NHTSA-mandated recall.