2000 Dodge Durango thermostat

Check the thermostat, it could possiblre make your engine run in open loop, here's the side effects.
* Coolant Thermostat monitor. On 2000 and newer vehicles, the OBD II system keeps an eye on the operation of the cooling system thermostat. Engine temperature is important because it affects emissions, fuel economy and engine wear. If the engine fails to reach normal operating temperature, it may prevent the fuel feedback system from going into closed loop. A cold engine usually requires a richer fuel mixture which wastes fuel and increases carbon monoxide emissions. A lower than normal operating temperature can also increase cylinder wear over a period of time, and blowby into the crankcase which increases oil dilution, shortens oil life and is hard on the engine's bearings. Engine coolant temperature related OBD II codes include P0115 to P0119, P0125, P0126, P0128 and P0217.

Amen brother Mike by letting the engine warm up as quickly as possible, the thermostat reduces engine wear, deposits and emissions-

For what engine? 4.7 or 5.9L

For 4.7 its gonna take an 1hr that can range from $70-$130.00 per hrly labor with the thermostat at $28.15

5.9L about the same in labor/part cost

Remove and Test the Thermostat
Step 1Turn off the engine and allow the engine to cool.

Step 2Remove the bolts holding the thermostat cap in place.

Step 3Lift off the housing cap to expose the thermostat. Pull the thermostat out of the housing with your fingers. Take careful note of which way it sits so that you can reinstall it or its replacement in the same position.

Step 4Put the thermostat in a pan of water on the stove, and turn the burner on high.

Step 5Monitor the water temperature with an oven thermometer. The thermostat should open at about 195 degrees F if it is functioning properly.

Step 6Replace a faulty thermostat. Reinstall it if it opens and closes properly, and look for another problem in the cooling system.

Or with the use of an infrared thermometer