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Geo Thermostat

2 items

Upgrade your vehicle's thermostat with A-Premium's high-quality options. Choose reliability and durability for a smoother ride.

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A-Premium APTHE017 Engine Coolant ThermostatA-Premium APTHE017 Engine Coolant Thermostat
A-Premium®Part # APTHE017
A-Premium APTHE017 Engine Coolant Thermostat
52 Reviews
CA$22.99
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2-year warranty
90 days free return
Fits 2008 - 2009 Ford F-650, 2008 - 2009 Ford F-750, 1999 - 2001 Toyota Solara, 1998 - 1998 Ford F-800, 1998 - 1998 Ford F-800 LPO, 1997 - 1998 Nissan 200SX, 1996 - 2000 Toyota RAV4, 1996 - 1997 Nissan Sentra, 1995 - 1995 Nissan 200SX, 1994 - 1997 Toyota Celica, 1993 - 1997 Geo Prizm, 1993 - 1997 Toyota Corolla, 1992 - 2001 Toyota Camry, 1992 - 1999 Toyota Celica, 1992 - 1999 Toyota Paseo, 1991 - 1993 Nissan NX, 1990 - 1993 Toyota Celica, 1989 - 1999 Nissan Sentra, 1989 - 1997 Geo Prizm, 1989 - 1990 Nissan Pulsar NX
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Geo
Item LocatedUnited States
Quantity1
MaterialMetal
ConditionNew
item #1005USAT
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A-Premium APTHE018 Engine Coolant Thermostat
A-Premium®Part # APTHE018
A-Premium APTHE018 Engine Coolant Thermostat
52 Reviews
CA$39.99
Edit ZIP code
2-year warranty
90 days free return
Fits 2008 - 2009 Ford F-650, 2008 - 2009 Ford F-750, 1999 - 2001 Toyota Solara, 1998 - 1998 Ford F-800, 1998 - 1998 Ford F-800 LPO, 1997 - 1998 Nissan 200SX, 1996 - 2000 Toyota RAV4, 1996 - 1997 Nissan Sentra, 1995 - 1995 Nissan 200SX, 1994 - 1997 Toyota Celica, 1993 - 1997 Geo Prizm, 1993 - 1997 Toyota Corolla, 1992 - 2001 Toyota Camry, 1992 - 1999 Toyota Celica, 1992 - 1999 Toyota Paseo, 1991 - 1993 Nissan NX, 1990 - 1993 Toyota Celica, 1989 - 1999 Nissan Sentra, 1989 - 1997 Geo Prizm, 1989 - 1990 Nissan Pulsar NX
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Geo
Item LocatedUnited States
Quantity1
MaterialMetal
ConditionNew
item #1005UU8S
Show less

What is an engine thermostat?

 While all engines can become too hot, if your thermostat isn't working correctly, your engine's well-being is at serious risk. The engine thermostat, often simply referred to as a thermostat, regulates the engine's operating temperature within an optimal range (typically around 195 to 220 degrees Fahrenheit).

How does a car thermostat work?

As a temperature-sensitive valve within the cooling system, a car thermostat responds to changes in coolant temperature. Understanding how it works by the following breakdown steps:

  • Closed position (cold start)

Initially closed to help the engine warm up quickly.

  • Heating up

The engine generates heat during operation.

  • Opening the thermostat

A temperature-sensitive element (usually wax) causes the thermostat to open gradually.

  • Coolant flow

When open, coolant flows from the engine to the radiator.

  • Maintaining optimal temperature

Adjusts coolant flow to maintain the ideal engine temperature.

  • Temperature regulation

Continuously adjusts to prevent overheating and ensure efficient operation.

Signs of a bad thermostat

  1. Overheating: The engine becomes excessively hot due to a stuck-closed thermostat.
  2. Low or fluctuating temperature: A thermostat stuck open results in a cooler engine, affecting fuel efficiency and heating.
  3. Temperature warning light: Illuminates to indicate engine overheating due to a faulty thermostat.
  4. Poor fuel efficiency: Stuck-open thermostat reduces fuel efficiency as the engine operates less efficiently at lower temperatures.
  5. Inadequate cabin heating: Insufficient cabin heating in cold weather with a thermostat that's stuck open.
  6. Coolant leaks: Gasket or sealing issues can lead to coolant leaks.
  7. Rapid temperature fluctuations: The gauge shows rapid swings between hot and cold.
  8. Engine running hot at idle: Higher engine temperature during idle or in traffic due to restricted coolant flow.
  9. Slow or inconsistent warm-up: Longer-than-normal warm-up times, even in moderate weather.
  10. Inconsistent heater operation: This affects the performance of the vehicle's heater, causing inconsistent or inadequate heating in cold weather.

Related Blogs

Why Does Coolant Boil After You Turn the Engine Off?

Learn why coolant boils or bubbles after you turn the engine off, how heat soak affects the cooling system, and how to diagnose leaks, trapped air, cap, thermostat, fan, water pump, or head gasket problems.

Jul 29, 2026