24/7 Customer service
To make aftermarket auto parts an afterthought.
Add your vehicle
Address
Login
Cart
Item
$0.00
Add your vehicle to ensure fitment/Choose a yearRequired Fields
Select a different vehicle
Make/Model
VIN
Save

Dodge Thermostat

56 items

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

  • All filters
  • Sort By
  • Year
  • Model
  • Price
  • Placement on Vehicle
  • Brand
  • Material
  • Color
  • Warranty
2 Pcs Engine Coolant Thermostat for Dodge Avenger 2008-2014 Jeep Compass 2007-20172 Pcs Engine Coolant Thermostat for Dodge Avenger 2008-2014 Jeep Compass 2007-2017
A-Premium®Part # APTHA0080
2 Pcs Engine Coolant Thermostat for Dodge Avenger 2008-2014 Jeep Compass 2007-2017
4.694 Reviews
$27.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2011 - 2014 Chrysler 200, 2009 - 2020 Dodge Journey, 2008 - 2014 Dodge Avenger, 2008 - 2010 Dodge Avenger, 2007 - 2017 Jeep Compass, 2007 - 2017 Jeep Compass, 2007 - 2017 Jeep Patriot, 2007 - 2017 Jeep Patriot, 2007 - 2012 Dodge Caliber, 2007 - 2012 Dodge Caliber, 2007 - 2010 Chrysler Sebring, 2007 - 2009 Dodge Caliber
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Installation PositionWater Inlet & Water Pass Through
ConditionNew
item #100593C2
Note
This item includes Primary, Secondary Thermostat and Seal.
Show less
A-Premium APTHA0273 Engine Coolant Thermostat Housing Assembly
A-Premium®Part # APTHA0273
A-Premium APTHA0273 Engine Coolant Thermostat Housing Assembly
4.694 Reviews
$36.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2016 - 2017 Fiat 500X, 2014 - 2017 Fiat 500L, 2013 - 2016 Dodge Dart, 2012 - 2017 Fiat 500
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
ColorNatural
ConditionNew
item #1005V08P
Show less
Thermostat Housing Assembly for Jeep Grand Cherokee Wrangler Dodge Durango
A-Premium®Part # APTHA0058C
Thermostat Housing Assembly for Jeep Grand Cherokee Wrangler Dodge Durango
4.694 Reviews
$30.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2018 - 2018 Jeep Wrangler JK, 2012 - 2017 Jeep Wrangler, 2011 - 2020 Jeep Grand Cherokee, 2011 - 2015 Dodge Durango
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
ColorBlack
ConditionNew
item #1003CZHK
Note
This part comes with a cover and thermostat and for Jeep Grand Cherokee 2014-2015, it only fits vehicles with flex engine,
Show less
Engine Coolant Thermostat Housing Assembly for Chrysler 300 Dodge Charger 11-21
A-Premium®Part # APTHA0038
Engine Coolant Thermostat Housing Assembly for Chrysler 300 Dodge Charger 11-21
4.694 Reviews
$23.99
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2011 - 2021 Chrysler 300, 2011 - 2021 Dodge Challenger, 2011 - 2021 Dodge Charger
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
ColorBlack
ConditionNew
item #10047TSG
Note
【Note-1】 This part comes with a cover and thermostat.
【Note-2】 It is original plastic designFit V6 3.6L Only.
Show less
A-Premium APTHE003 Engine Coolant Thermostat
A-Premium®Part # APTHE003
A-Premium APTHE003 Engine Coolant Thermostat
4.694 Reviews
$20.99
Low stock: Only 3 left
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2013 - 2021 Blue Bird Vision School Bus, 2006 - 2008 Lincoln Mark LT, 2005 - 2006 Mercury Monterey, 2005 - 2006 Volkswagen Jetta, 2002 - 2010 Mercury Mountaineer, 2002 - 2002 Lincoln Blackwood, 1998 - 2014 Lincoln Navigator, 1995 - 1995 Toyota Pickup, 1994 - 1997 Mercury Cougar, 1994 - 1995 Saab 900, 1992 - 2011 Mercury Grand Marquis, 1992 - 1992 Isuzu Stylus, 1992 - 1992 Saab 9000, 1991 - 2011 Lincoln Town Car, 1991 - 1993 Saab 900, 1990 - 1995 Saab 9000, 1990 - 1991 Peugeot 405, 1989 - 1989 Peugeot 405, 1987 - 1988 Mazda RX-7, 1986 - 1990 Saab 9000
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
MaterialMetal and Rubber
ConditionNew
item #1005V2KW
Show less
Engine Coolant Thermostat Housing Assembly for Benz W463 G550 Freightliner Dodge
A-Premium®Part # APTHA0068
Engine Coolant Thermostat Housing Assembly for Benz W463 G550 Freightliner Dodge
4.694 Reviews
$61.99
Low stock: Only 4 left
Enter ZIP codeFree standard shipping
2-year warranty
90 days free return
Fits 2010 - 2011 Mercedes-Benz E550, 2009 - 2015 Mercedes-Benz G550, 2008 - 2012 Mercedes-Benz GL550, 2008 - 2011 Mercedes-Benz ML550, 2008 - 2011 Mercedes-Benz S450, 2008 - 2008 Mercedes-Benz R550, 2007 - 2012 Mercedes-Benz GL450, 2007 - 2012 Mercedes-Benz SL550, 2007 - 2011 Mercedes-Benz S550, 2007 - 2010 Mercedes-Benz CL550, 2007 - 2008 Dodge Sprinter 2500, 2007 - 2008 Dodge Sprinter 3500, 2007 - 2008 Freightliner Sprinter 2500, 2007 - 2008 Freightliner Sprinter 3500
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
ColorSilver
ConditionNew
item #1000GX4U
Show less
Vemo V25-99-1707 Engine Coolant Thermostat
VemoPart # V25-99-1707
Vemo V25-99-1707 Engine Coolant Thermostat
4.99 Reviews
$22.99
Low stock: Only 2 left
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2006-2006 Chrysler Sebring, 2004-2005 Chrysler Sebring, 2004-2005 Chrysler Sebring, 2004-2005 Chrysler Sebring, 2003-2005 Dodge SX 2.0, 2001-2010 Chrysler PT Cruiser, 2001-2004 Chrysler Sebring, 2001-2004 Chrysler Sebring, 2001-2003 Chrysler Sebring, 2000-2003 Chrysler Voyager, 2000-2002 Chrysler Neon, 2000-2000 Chrysler Cirrus, 2000-2000 Chrysler Grand Voyager, 2000-2000 Chrysler Voyager, 2000-2000 Ford Explorer, 2000-2000 Ford Explorer, 1999-2000 Chrysler Cirrus, 1999-2000 Dodge Grand Caravan, 1999-2000 Dodge Grand Caravan, 1999-2000 Ford Explorer
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
V25-99-1707, 78355S, 5204888, 20187J, 20188J, 24688, 25488, 18973, 
...View more
item #1001QQDL
Note
With seal
Show less
ÜRO Parts 6462001215 Engine Coolant Thermostat Housing Assembly
ÜRO PartsPart # 6462001215
ÜRO Parts 6462001215 Engine Coolant Thermostat Housing Assembly
52 Reviews
$44.99
Low stock: Only 3 left
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2006-2006 Mercedes-Benz E320, 2005-2005 Mercedes-Benz E320, 2004-2006 Mercedes-Benz Sprinter, 2003-2006 Dodge Sprinter 2500, 2003-2006 Dodge Sprinter 3500, 2002-2006 Freightliner Sprinter 2500, 2002-2006 Freightliner Sprinter 3500
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
6462001215, 5080146AA, 5080146AB, 05080146AA, 05080146AB, 6462001215, 37456, 34700, 
...View more
item #1000ZQ0E
Show less
Vemo V20-99-1280 Engine Coolant Thermostat
VemoPart # V20-99-1280
Vemo V20-99-1280 Engine Coolant Thermostat
4.99 Reviews
$25.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2008-2008 Mini Cooper, 2008-2008 Mini Cooper, 2008-2008 Mini Cooper, 2007-2008 Mini Cooper, 2007-2008 Mini Cooper, 2007-2008 Mini Cooper, 2007-2008 Mini Cooper, 2007-2007 Mini Cooper, 2007-2007 Mini Cooper, 2006-2006 Chrysler Pacifica, 2006-2006 Chrysler Pacifica, 2004-2006 Chrysler Pacifica, 2002-2008 Mini Cooper, 2002-2008 Mini Cooper, 2001-2006 Chrysler Town & Country, 2001-2006 Dodge Caravan, 2001-2006 Dodge Grand Caravan, 2001-2003 Chrysler Voyager
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
V20-99-1280, 78524, 34091, 11531485847, 11537512733, 11537596787, 11531501173, 1601480902, 
...View more
item #1001QR60
Note
With seal
Show less
ÜRO Parts CY0719439 Engine Coolant Thermostat Housing, Lower
ÜRO PartsPart # CY0719439
ÜRO Parts CY0719439 Engine Coolant Thermostat Housing, Lower
52 Reviews
$37.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2019-2022 Ram 1500 Classic, 2019-2021 Ram ProMaster 2500, 2019-2019 Ram ProMaster 3500, 2018-2021 Ram ProMaster 1500, 2018-2018 Ram ProMaster 2500, 2016-2022 Jeep Cherokee, 2016-2017 Ram ProMaster 2500, 2015-2015 Jeep Cherokee, 2015-2015 Ram ProMaster 2500, 2014-2018 Ram ProMaster 3500, 2014-2017 Ram ProMaster 1500, 2014-2014 Jeep Cherokee, 2014-2014 Ram ProMaster 2500, 2013-2019 Dodge Journey, 2013-2018 Ram 1500, 2012-2022 Dodge Challenger, 2012-2022 Dodge Charger, 2012-2015 Dodge Durango, 2012-2015 Jeep Grand Cherokee, 2012-2015 Ram C/V
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Installation PositionLower
ColorBlack
item #1000ZRXH
Show less
Vemo V30-99-0187 Engine Coolant Thermostat
VemoPart # V30-99-0187
Vemo V30-99-0187 Engine Coolant Thermostat
4.99 Reviews
$76.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2012-2012 Mercedes-Benz GL550, 2012-2012 Mercedes-Benz SL550, 2011-2011 Mercedes-Benz SL550, 2010-2011 Mercedes-Benz E550, 2009-2015 Mercedes-Benz G550, 2008-2011 Mercedes-Benz GL550, 2008-2011 Mercedes-Benz ML550, 2007-2012 Mercedes-Benz GL450, 2007-2011 Mercedes-Benz S550, 2007-2010 Mercedes-Benz CL550, 2007-2009 Mercedes-Benz SL550, 2007-2008 Dodge Sprinter 2500, 2007-2008 Dodge Sprinter 3500
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
V30-99-0187, TM29100D, 669100, 8620340100, 2722000515, 2732000215, A2722000515, A2732000215, 
...View more
item #1001QLU5
Note
With seal
Show less
Beck/Arnley 143-0935 Engine Coolant Thermostat Housing Assembly
Beck/ArnleyPart # 143-0935
Beck/Arnley 143-0935 Engine Coolant Thermostat Housing Assembly
52 Reviews
$45.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2013-2016 Dodge Dart, 2012-2017 Fiat 500
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
143-0935
item #1000XAAR
Show less
Beck/Arnley 143-0545 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0545
Beck/Arnley 143-0545 Engine Coolant Thermostat
52 Reviews
$30.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2006-2008 Toyota Solara, 2004-2006 Toyota Matrix, 2003-2003 Toyota Solara, 2001-2009 Mazda B4000, 1997-1997 Mercedes-Benz E320, 1996-1997 Jaguar Vanden Plas, 1996-1996 Jaguar XJS, 1995-1997 Jaguar XJR, 1995-1997 Mercedes-Benz C36 AMG, 1994-1999 Mercedes-Benz S320, 1994-1997 Mercedes-Benz C280, 1994-1997 Mercedes-Benz SL320, 1994-1996 Mercedes-Benz E320, 1994-1995 Jaguar XJS, 1993-1993 Jaguar XJS, 1993-1993 Mercedes-Benz 300E, 1990-1993 Mercedes-Benz 300SL, 1990-1992 Eagle Premier, 1990-1992 Mercedes-Benz 300E, 1990-1991 Dodge Monaco
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0545
item #1000XH2D
Show less
ÜRO Parts 2722000515 Engine Coolant Thermostat / Water Inlet Assembly
ÜRO PartsPart # 2722000515
ÜRO Parts 2722000515 Engine Coolant Thermostat / Water Inlet Assembly
52 Reviews
$76.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2014-2015 Mercedes-Benz G500, 2013-2013 Mercedes-Benz G500, 2012-2012 Mercedes-Benz CL500, 2012-2012 Mercedes-Benz E500, 2011-2012 Mercedes-Benz E250, 2010-2011 Mercedes-Benz CL500, 2010-2011 Mercedes-Benz CLS350, 2010-2011 Mercedes-Benz E500, 2010-2011 Mercedes-Benz E550, 2010-2011 Mercedes-Benz S500, 2010-2010 Mercedes-Benz E300, 2009-2014 Mercedes-Benz G550, 2009-2012 Mercedes-Benz G500, 2008-2012 Mercedes-Benz GL500, 2008-2012 Mercedes-Benz GL550, 2008-2011 Mercedes-Benz ML500, 2008-2011 Mercedes-Benz ML550, 2008-2011 Mercedes-Benz S450, 2008-2008 Mercedes-Benz R550, 2007-2012 Mercedes-Benz GL450
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
2722000515, 68013949AA, 2732000215, 2722000515, 902-5903, 86039, TM29100D, 940-212, 
...View more
item #1000ZSG2
Show less
Beck/Arnley 143-0412 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0412
Beck/Arnley 143-0412 Engine Coolant Thermostat
52 Reviews
$31.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 1997-1997 Mercedes-Benz E320, 1994-1999 Mercedes-Benz S320, 1994-1997 Mercedes-Benz C280, 1994-1996 Mercedes-Benz E320, 1994-1995 Mercedes-Benz SL320, 1993-1993 Mercedes-Benz 300E, 1990-1993 Mercedes-Benz 300SL, 1990-1992 Eagle Premier, 1990-1992 Mercedes-Benz 300E, 1990-1991 Dodge Monaco, 1990-1990 Peugeot 505, 1989-1990 Peugeot 505, 1989-1990 Volvo 780, 1989-1989 Peugeot 505, 1988-1993 Mercedes-Benz 300CE, 1988-1993 Mercedes-Benz 300SE, 1988-1992 Jaguar XJ6, 1988-1991 Mercedes-Benz 300SEL, 1988-1990 Peugeot 505, 1988-1990 Volvo 760
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0412
item #1000XK1D
Show less
Beck/Arnley 143-0636 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0636
Beck/Arnley 143-0636 Engine Coolant Thermostat
52 Reviews
$28.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2005-2007 Mercedes-Benz SL65 AMG, 2004-2007 Mercedes-Benz SL600, 1999-1999 Mercedes-Benz S500, 1998-1999 Mercedes-Benz CL600, 1997-1997 Mercedes-Benz E320, 1995-1998 Mercedes-Benz S500, 1995-1998 Mercedes-Benz SL500, 1994-2002 Mercedes-Benz SL600, 1994-1999 Mercedes-Benz S320, 1994-1999 Mercedes-Benz S600, 1994-1997 Mercedes-Benz C280, 1994-1997 Mercedes-Benz SL320, 1994-1996 Mercedes-Benz E320, 1993-1993 Mercedes-Benz 300E, 1990-1993 Mercedes-Benz 300SL, 1990-1992 Eagle Premier, 1990-1992 Mercedes-Benz 300E, 1990-1991 Dodge Monaco, 1990-1990 Peugeot 505, 1989-1990 Peugeot 505
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
QuantityOne Set
Part interchange
143-0636
item #1000XGZX
Show less
Beck/Arnley 143-0081 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0081
Beck/Arnley 143-0081 Engine Coolant Thermostat
52 Reviews
$20.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 1995-1997 Toyota Celica, 1994-1996 Jaguar XJ12, 1992-1992 Jaguar XJS, 1990-1992 Nissan D21, 1989-1993 Saab 900, 1989-1990 Peugeot 505, 1989-1990 Peugeot 505, 1989-1989 Peugeot 505, 1987-1988 Peugeot 505, 1987-1988 Saab 900, 1987-1987 Jaguar XJ6, 1987-1987 Peugeot 505, 1986-1993 Saab 9000, 1986-1988 Mazda RX-7, 1986-1988 Saab 900, 1986-1986 Saab 900, 1985-1988 Saab 900, 1985-1986 Peugeot 505, 1984-1985 Mazda RX-7, 1983-1986 Nissan 720
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
143-0081
item #1000XHXT
Show less
Beck/Arnley 143-0688 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0688
Beck/Arnley 143-0688 Engine Coolant Thermostat
52 Reviews
$27.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2001-2005 Kia Rio, 1999-1999 Chevrolet Tracker, 1999-1999 Chevrolet Tracker, 1999-1999 Chevrolet Tracker, 1998-1998 Chevrolet Tracker, 1997-1998 Mitsubishi 3000GT, 1996-1998 Suzuki X-90, 1996-1996 Mitsubishi Diamante, 1994-1997 Ford Aspire, 1994-1997 Mazda Miata, 1994-1994 Mitsubishi Montero, 1993-1996 Mitsubishi Mirage, 1992-1996 Eagle Summit, 1992-1995 Hyundai Elantra, 1992-1995 Mitsubishi Diamante, 1992-1993 Dodge Grand Caravan, 1992-1992 Eagle Summit, 1992-1992 Mitsubishi Expo, 1991-1994 Mercury Capri, 1991-1992 Hyundai Scoupe
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
143-0688
item #1000XGE3
Show less
Beck/Arnley 143-0689 Engine Coolant Thermostat
Beck/ArnleyPart # 143-0689
Beck/Arnley 143-0689 Engine Coolant Thermostat
52 Reviews
$23.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2007-2009 Suzuki SX4, 2003-2003 Suzuki Vitara, 2002-2007 Suzuki Aerio, 2002-2002 Suzuki Esteem, 1999-2002 Suzuki Vitara, 1999-2001 Suzuki Esteem, 1999-1999 Chevrolet Tracker, 1999-1999 Chevrolet Tracker, 1999-1999 Chevrolet Tracker, 1999-1999 Mitsubishi 3000GT, 1998-1998 Chevrolet Tracker, 1997-1998 Mitsubishi 3000GT, 1996-1998 Suzuki X-90, 1996-1996 Mitsubishi Diamante, 1994-1997 Ford Aspire, 1994-1997 Mazda Miata, 1994-1994 Mitsubishi Montero, 1993-1996 Mitsubishi Mirage, 1992-1996 Eagle Summit, 1992-1995 Hyundai Elantra
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
Part interchange
143-0689
item #1000XHG9
Show less
ÜRO Parts CY0714523 Engine Coolant Thermostat / Water Inlet Assembly
ÜRO PartsPart # CY0714523
ÜRO Parts CY0714523 Engine Coolant Thermostat / Water Inlet Assembly
52 Reviews
$91.99
Enter ZIP codeFree standard shipping
3-year warranty
90 days free return
Fits 2020-2020 Dodge Journey, 2019-2019 Dodge Journey, 2012-2014 Dodge Avenger, 2011-2014 Chrysler 200, 2011-2011 Dodge Avenger, 2011-2011 Dodge Avenger, 2011-2011 Dodge Avenger, 2010-2012 Dodge Caliber, 2009-2018 Dodge Journey, 2009-2017 Jeep Compass, 2009-2017 Jeep Patriot, 2009-2010 Chrysler Sebring, 2009-2010 Dodge Avenger, 2009-2009 Dodge Caliber, 2009-2009 Dodge Caliber, 2009-2009 Dodge Caliber, 2009-2009 Dodge Caliber, 2009-2009 Dodge Caliber, 2009-2009 Dodge Caliber, 2008-2008 Dodge Avenger
Add Trim and Engine info to ensure a guaranteed fit
Vehicle: Dodge
Item LocatedUnited States
Quantity1
ColorBlack
Part interchange
CY0714523, 68003582AB, 55111017AD, 4884571-AB, 4884873-AA, 55111016AD, 55111016AE, 55111017AC, 
...View more
item #1000ZUCR
Show less
Page 2 of 3

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