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Thermostat Replacement

Moderate

Thermostat replacement involves draining some coolant, removing the thermostat housing, and swapping the old thermostat for a new one. The thermostat regulates engine temperature by controlling coolant flow to the radiator. A stuck-open thermostat causes slow warm-up and poor heater performance, while a stuck-closed thermostat causes overheating.

Estimated time: 1-2 hours

Cost Breakdown

DIY (Parts Only)

$20 - $75

Professional Shop

$150 - $350

Prices vary by location, vehicle make/model, and shop rates.

Tools Needed

  • Socket wrench set
  • Drain pan
  • Gasket scraper
  • Torque wrench
  • Coolant

Step-by-Step Instructions

1

Allow the engine to cool completely. Partially drain the cooling system into a drain pan to bring the coolant level below the thermostat housing.

2

Locate the thermostat housing — follow the upper radiator hose to where it connects to the engine.

3

Remove the hose clamp and disconnect the radiator hose from the housing.

4

Remove the thermostat housing bolts and lift the housing off. Note the orientation of the old thermostat.

5

Remove the old thermostat and clean all gasket material from both mating surfaces with a scraper.

6

Install the new thermostat with the spring side facing into the engine. Install a new gasket or apply sealant as specified.

7

Reinstall the housing, torque the bolts to spec, reconnect the hose, and refill the cooling system. Bleed air from the system by running the engine with the heater on.

Tips & Warnings

  • Make sure the new thermostat has the same temperature rating as the original (usually 180-195 degrees F).
  • A thermostat stuck closed is an emergency — pull over immediately if the temperature gauge enters the red zone.
  • Test a suspect thermostat by placing it in a pot of water and heating it. It should open near its rated temperature.
  • Always use a new gasket or O-ring with the new thermostat to prevent coolant leaks.

Related OBD-II Codes

P0128Coolant Thermostat Below Thermostat Regulating TemperatureP0125Insufficient Coolant Temperature for Closed Loop Fuel ControlP0116Engine Coolant Temperature Circuit Range/PerformanceP0117Engine Coolant Temperature Sensor Circuit Low Input

Related Recalls

Recommended Parts & Tools

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