What would cause a thermostat to stick?

Author: Fidel Johnson  |  Last update: Thursday, February 13, 2025

Due to corrosion or aging, your car's thermostat can get stuck in a closed position. If this happens, the thermostat will not let the coolant reach the radiator, and, as mentioned above, the engine will overheat, causing severe damage.

How to stop a thermostat from sticking?

This is an easy problem to solve yourself by simply removing the plastic outer casing and, with a very soft brush, delicately brushing off its coil and contact surfaces. It is most effective to clean the thermostat first at its lowest setting, then again at its highest setting.

What causes the thermostat to stick?

Contaminated fluids: The thermostat essentially works as a gateway for coolant that flows through the cooling system. Excessive contamination of that fluid can cause deposits around the thermostat, causing it to get stuck.

What are the symptoms of a bad thermostat?

What Are the Signs of a Bad or Broken Thermostat?
  • The AC or Furnace Won't Come On. ...
  • The HVAC System Won't Turn Off. ...
  • The Thermostat Is Unresponsive. ...
  • The HVAC System Short-Cycles. ...
  • The Room Temperature Doesn't Match the Thermostat Setting. ...
  • The Programmed Settings Reset Themselves. ...
  • Check and Adjust the Settings.

Is it okay to drive a car with a stuck thermostat?

Yes, you can drive a car with a thermostat stuck open, but it's not ideal and could lead to several problems over time.

How to Tell Car Thermostat Is Bad (Symptoms of Stuck Open Stuck Closed and Overheating)

Why is my thermostat stuck on one temperature?

If this doesn't work, try resetting your thermostat with the reset button, changing the batteries, or cleaning off any dust and dirt inside. If the temperature is still stuck, an electrical or display issue might be to blame. Contact an HVAC professional for further help.

How much does it cost to fix a stuck thermostat in a car?

Car thermostat replacement time is 30 to 60 minutes, depending on the make of the car. It will cost you around $190 to $350, including labor. Thermostat repairs usually take more time, requiring extra time to diagnose and analyze the vehicle's thermostat. It can take up to 2 hours.

How do I know if my thermostat or sensor is bad?

Symptoms of bad temperature sensor
  1. Erratic Readings. Sudden jumps or drops in temperature readings. ...
  2. Open Circuit: Display shows a very high or infinite temperature. ...
  3. Short Circuit: Display shows a very low or negative temperature. ...
  4. Drift: ...
  5. Noise or Interference: ...
  6. Physical Damage:

What are the symptoms of a bad head gasket?

Common Signs of a Bad Head Gasket
  • Coolant Loss: Keep an eye on your coolant levels — a significant drop is a red flag. ...
  • White Smoke from the Tailpipe: Some white smoke from the exhaust pipe of a cold engine is normal. ...
  • Engine Knocking: Blown head gaskets can lead to poor compression. ...
  • Milky Oil: Check your engine's oil.

How much does it cost to replace a thermostat?

The average cost of a new thermostat, including installation, ranges in price from $50 to $500 or more based on several factors including the type of thermostat, labor costs, the complexity of the installation, and more.

How do you reset a stuck thermostat?

Turn your thermostat to the 'off' position... Then venture off to your home's breaker box. Find the breaker to your HVAC system, flipping it 'off'. Make sure the breaker is flipped all the way 'off,' then wait for 30-seconds. Turn the breaker back 'on.

How far can I drive with a bad thermostat?

The furthest you can drive an overheating car is about a ¼ mile before you risk irreversible engine damage. While some vehicles could still make it as far as 20 miles, we would never recommend driving very far with an overheating engine.

What are the symptoms of a bad water pump?

6 signs your water pump is failing ​
  • Coolant Leak. The water pump has several gaskets that can be damaged or worn out over time. ...
  • Engine Overheating. ...
  • High Pitched, Harmonic Whining Noises. ...
  • Water Pump Rust and Corrosion. ...
  • Steam comes out from under your hood. ...
  • Holes or leakage system on the dry side of the water pump.

What happens if thermostat sticks?

Overheating is the most common symptom of a failing thermostat. Due to corrosion or aging, your car's thermostat can get stuck in a closed position. If this happens, the thermostat will not let the coolant reach the radiator, and, as mentioned above, the engine will overheat, causing severe damage.

Why is my thermostat stuck on hold?

The Permanent Hold feature keeps your home's temperature at the same temperature indefinitely until you manually cancel it. If you can't reprogram your thermostat's temperature, this is likely the cause. You should be back on your programmed schedule as soon as you cancel it.

Will a stuck thermostat cause a leak?

A thermostat leak is usually caused by movement in the coolant rubber hose, damaged housing, and a worn seal. The common symptoms of a thermostat housing leak are a stuck thermostat valve, an illuminated low coolant warning light, and the P0128 or P0125 code.

What can be mistaken for a blown head gasket?

A lot of the problem is due to the similarity between issues with head gaskets and other engine components, such as the following: A chipped or warped cylinder head, which could affect the head gasket, but wouldn't necessarily be the result of a blown head gasket.

How do I know if I have a blown head gasket or cracked block?

Conducting a compression test on each cylinder is a valuable diagnostic tool for identifying both a blown head gasket and a cracked block. Significant variation in compression levels between cylinders could indicate a blown head gasket, as the gasket's failure can affect the seal between cylinders.

How does a car act with a blown head gasket?

One of the most common symptoms is an engine that runs poorly. It might have a rough idle, deliver poor acceleration, overheat, or exhibit a combination of all three issues. This happens because the engine makes less power as it loses compression.

How can I test if my thermostat is bad?

7 Ways to Tell Your Thermostat Is Broken
  1. The Thermostat Has No Power. ...
  2. The AC or Furnace Won't Turn On. ...
  3. The Heater or AC Won't Turn Off. ...
  4. The Thermostat Reading Doesn't Match the Room Temperature. ...
  5. The Thermostat Doesn't Respond. ...
  6. The HVAC System Is Short Cycling. ...
  7. The Thermostat Forgets Programmed Settings.

What happens if I unplug the coolant temperature sensor?

It's not recommended to unplug the coolant temperature sensor unless necessary for diagnostic purposes, as it can adversely affect engine operation and potentially cause damage if left unplugged for an extended period.

Will a bad thermostat throw a code?

While there is a small chance that there is an issue with the running temperature of your engine, by far the most common issue with trouble code P0128 is a faulty thermostat. The exact location of the thermostat and issues related to a damaged thermostat may vary depending on your vehicle.

How many hours does it take to replace a thermostat?

Installation typically takes about 1 hour.

What happens if you keep driving with a bad thermostat?

If you drive with a bad thermostat, your car could overheat, causing severe and expensive engine damage. And while it's technically possible to drive without a thermostat, we don't recommend it. Your car will not reach an acceptable operating temperature, resulting in higher fuel consumption and excessive engine wear.

What is the life expectancy of a car thermostat?

A car thermostat is designed to last a long time – typically around 100,000 miles or 10 years. However, various factors can impact its lifespan. First, driving conditions play a role. If you regularly drive in hot weather or stop-and-go traffic, your thermostat may suffer additional stress.

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