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Shopping for 2003-Nissan-Altima
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Thermostat

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Engine Coolant Thermostat
A-Premium®
A-Premium APTHE054 Engine Coolant Thermostat
$20.99
$22.99
Quantity Less than 3
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2-year warranty
90 days free return
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
Part interchange
7427-180, 427180, 33941, 33941S, TH631482, 78645, 1430818, THN011, 
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ConditionNew
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Thermostat Housing Assembly
A-Premium®
Thermostat Housing Assembly for INFINITI I35 2002-2004 Nissan Altima 2002-2006
$30.99
$32.99
Only 1 item left in stock
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2-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
MaterialAluminum
Part interchange
902-5125, 431180, 85688, 212008J10B, 212008J100
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Engine Coolant Thermostat
A-Premium®
A-Premium APTHE004 Engine Coolant Thermostat
$29.99
$31.99
Only 1 item left in stock
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2-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
Part interchange
2028-170, 2028170
ConditionNew
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Engine Coolant Thermostat
A-Premium®
Engine Coolant Thermostat for Nissan Altima 2002-2013 Rogue Sentra INFINITI
$22.99
$24.99
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2-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
7457-205, 457205, 34160, THN020, TH730095J, THN001, 15112, 212303RC0A, 
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ConditionNew
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Beck/Arnley 143-0833 Engine Coolant Thermostat
Beck/Arnley
Beck/Arnley 143-0833 Engine Coolant Thermostat
$32.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0833
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Beck/Arnley 143-0815 Engine Coolant Thermostat Housing Assembly
Beck/Arnley
Beck/Arnley 143-0815 Engine Coolant Thermostat Housing Assembly
$41.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0815
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Beck/Arnley 143-0717 Engine Coolant Thermostat
Beck/Arnley
Beck/Arnley 143-0717 Engine Coolant Thermostat
$24.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0717
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Beck/Arnley 143-0818 Engine Coolant Thermostat
Beck/Arnley
Beck/Arnley 143-0818 Engine Coolant Thermostat
$30.99
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3-year warranty
90 days free return
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
143-0818
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Engine Coolant Thermostat - Mahle TI 255 82D
Mahle
Engine Coolant Thermostat - Mahle TI 255 82D
$46.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
TI 255 82D, 21200-8J100, 21200-8J10B, 33951, 14778, TI25582D, 431-180
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Engine Coolant Thermostat - Mahle TX 145 82D
Mahle
Engine Coolant Thermostat - Mahle TX 145 82D
$29.99
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3-year warranty
90 days free return
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
TX 145 82D, 21200-6N210, 21200-EA000, 33941, 14678, TX14582D, 427-180
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Engine Coolant Thermostat - Mahle TX 170 77
Mahle
Engine Coolant Thermostat - Mahle TX 170 77
$24.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
TX 170 77, 21200-OC811, 34011, 48447, TX17077, 2028-170
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Engine Coolant Thermostat - Upper - Mahle TX 168 95
Mahle
Engine Coolant Thermostat - Upper - Mahle TX 168 95
$29.99
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3-year warranty
90 days free return
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Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Installation PositionUpper
Part interchange
TX 168 95, 21230-6N20A, 34160, 15112, TX16895, 7302-180
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Vemo V25-99-1710 Engine Coolant Thermostat
Vemo
Vemo V25-99-1710 Engine Coolant Thermostat
$34.99
Quantity Less than 2
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3-year warranty
90 days free return
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: 2003 Nissan Altima
Item LocatedUnited States
Quantity1
Part interchange
V25-99-1710, 78276S, 78459S, 78645, 78289, 22892, 42288, 23382, 
...View more
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.