The thermostat may fail to close completely, causing the Check Engine Light to illuminate. This problem will prevent the engine from reaching normal operating temperature; a new thermostat should be installed.Google+
Car Problem Reports
Chrysler Aspen Hybrid Check Engine Light Due to Failed Thermostat
Chrysler Aspen Hybrid Problem
Model Year Affected: 2009
Visitor, 2009 Chrysler Aspen Hybrid, 50,000 mi
The temperature gauge will not climb past the cold indication in the winter below 20 degrees, suspect the thermostat is stuck in the open position. Cannot get any heat out of the vents.