THERMO Valve
California models with 2.3L engine do not use a thermo valve. On all other models, the valve senses engine coolant temperature, and controls the vacuum circuit of the EGR valve.
At coolant temperatures above 130°F (55°C) on 2.0L engines or 140°F (60°C) on 2.3L engines, the thermo valve opens and supplies vacuum to EGR valve. At temperatures below this level, the valve is closed and EGR valve is not activated.