While your vehicle might have a ton of larger components that you think of, all the small components are essential to a smooth operation too. One of those small components that are essential to the smooth operation of your vehicle is the thermostat.
But what happens when the thermostat stops working the way it should and how much is it going to cost to get your vehicle back on the road? We’ll break down everything you need to know here.
How Your Car Thermostat Works
Before you can dive too far into the issues you might have with a faulty car thermostat you need to understand how the thermostat works and what it does in the first place.
The truth is that your car’s thermostat is a relatively simple component. It’s a valve that opens up once the coolant reaches a certain temperature. This sends the coolant throughout the rest of the engine and radiator to help cool everything down.
Once the temperature drops back below the preset point, the thermostat closes allowing the coolant to warm back before the thermostat opens back up again.
As an Amazon Associate I earn from qualifying purchases.
6 Bad Thermostat Symptoms
Before you go out and replace any components you need to pin down what the problem is. And that all starts with identifying the symptoms of a faulty thermostat. We’ve highlighted six different symptoms that could be saying your vehicle has a faulty thermostat.
Quick wins for a faster PC:
Clear out junk files and repair common Windows errorsFree Scan →Scan for outdated or missing drivers - takes under a minuteDriver Scan →1. Overheating Engine
The most common symptom of a faulty thermostat is an overheating engine. This happens when the thermostat fails in a closed position. When that happens the thermostat won’t open up and allow coolant to circulate throughout the engine.
Without the coolant the engine will overheat. Most engines have a failsafe that will shut off the engine when it reaches a certain temperature to keep it from blowing up, but that will still leave you stranded with a vehicle you can’t start up.
#1 Best Overall
- 【Notice】Please make sure to read the installation and wiring instructions provided in the pictures carefully before buying. If you are inexperienced with installation, it is advised to be cautious when making a purchase to avoid issues like product failure or incompatibility. (Verify the existing base to ensure only 2 to 5 wires are compatible for installation and wiring).
- 【Thermostat Applications 1H/1C】for with Conventional Single-Stage Heating & Air Conditioning, up to 1 Heat and 1 Cool. Gas/Oil/Electric Furnace (Heat only), Boiler Radiant (Heat only), Furnace Forced-Air (Heat Only), Gas Fireplace (24 Volts), Cooling Only, Only 1H/1C Heat Pump (without aux) Systems.
- 【Incompatible Systems】Does not work multistage systems (1H/2C, 2H/2C), HVAC heat pump systems (2H/1C, 4H/2C), PTACs, 3-wire hydronic (hot water), dual fuel/hybrid heating. Does not work line voltage systems (120-240V electric baseboards heat); mini split heat pump air conditioner, RV air conditioners mach and roughneck series.
- Suuwer S705 5-1-1 day programmable thermostat 1 Heat/ 1 Cool. Separate programs for the weekdays and weekends with 4 program periods per day including wake, leave, return and sleep.
- 【Technical support】 Separate heat or cool swing set up (0.2°F to 2°F) and 5 minute compressor delay protection (Selectable ON or OFF). Digital thermostat has a built-in battery change and filter change reminders (Set 50-2000 hours)
2. Engine Heats Up Slowly
While an overheating engine is the most common sign of a faulty thermostat, that won’t happen if the thermostat fails in the open position. When this happens, coolant is constantly circulating throughout your engine, which keeps your engine cooler than it should be.
Keep an eye on the temperature gauge inside your vehicle, and if it’s not heating up, that’s a classic sign of a faulty thermostat.
3. Fluctuating Engine Temperatures
Sometimes the thermostat doesn’t stay fully stuck in the open or closed position and it starts behaving erratically. When this happens it’s still a faulty thermostat, but you’re going to see the temperature gauge start jumping up and down at different times.
A properly functioning thermostat keeps your engine at the same temperature, a faulty one won’t do it very effectively.
Rank #2
- PRIVACY PROTECTION*: Sensi won’t sell your personal information to third parties
- EASY DIY INSTALLATION: Use the built-in level and step-by-step app instructions for a quick installation. Works with HVAC equipment found in most homes. Common wire (c-wire) is not required in most applications
- SAVE ABOUT 23% ON HVAC ENERGY*: The ENERGY STAR-certified Sensi smart thermostat can help you save energy with features like flexible scheduling, remote access and usage reports
- SIMPLE CONFIGURATION: Looks and feels like a thermostat. Has buttons and fits the same space as a traditional thermostat so you don’t have to patch and paint your walls
- SMART MAINTENANCE: Sensi can help monitor the performance and efficiency of your HVAC system by delivering valuable usage reports, alerts about your equipment, and maintenance reminders like filter replacement
4. Leaking Coolant
Your vehicle’s engine has a safety feature that dumps coolant out an overflow valve if it starts to get too hot. If the thermostat isn’t working properly, the engine and the coolant can get hotter than it should, and that will send the excess coolant out of the overflow valve.
Typically that overflow valve goes straight to the ground, and you’ll notice coolant on the ground when that happens.
5. Steaming Engine
While the coolant overflow valve typically goes straight to the ground, that’s not always the case. If the coolant dumps onto the hot engine, it’s going to create a lot of steam. There’s a good chance you’ll still end up with a lot of coolant on the ground, but you’ll also notice a lot of steam coming from the engine bay.
Rank #3
- · High Compatibility: Forced air (gas, oil or electric), Electric furnace, Hot water steam or gravity radiant heat, Heat only systems, Heat pump w/o auxiliary or emergency heat, Millivolt, Gas fireplaces (24V), Floor or wall furnaces, Cool only systems.(TIP: Before purchasing, check to see if this thermostat is compatible with your system.)
- · Not Compatible: Heat pump with auxiliary or emergency heat, Dual fuel/hybrid heating, Electric baseboard heat (110-240 volts), Line voltage, Convectors, Radiant-ceiling heat, Mini split systems and 12V RV systems.
- · Easy to Install and Use: Large terminal blocks with universal sub-base, can be installed within 30 minutes, Large, clear, easy-to-read backlight LCD display and easy controls make for a user-friendly experience.
- · Factory Pre-set Energy-efficiency Program: 7-day, 5/1/1 easy-to-understand programming menus, flexible programming lets you sync your comfort with your schedule.
- · Reliability: Made by professional manufacturer and backed by over 20 years of experience, the customer service is 7*24 hrs available.
6. Fluctuating Heater Temperature
You generally don’t think of the heater inside your vehicle when you’re thinking of bad car thermostat symptoms, it’s more common than you might think.
That’s because the heater system in your vehicle works by passing air over the warm coolant. So if the coolant can’t get to or stay at the right temperature, you’ll notice problems with the heater system in your vehicle.
How To Fix a Faulty Thermostat
Once you’ve identified the common symptoms of a bad thermostat, it’s time to dive into how to fix the problem. Because your car’s thermostat is a relatively inexpensive component, it doesn’t make much sense to try and repair it.
Rank #4
- An Alexa thermostat - Amazon Smart Thermostat is an easy way to switch from a traditional thermostats for homes and help reduce energy usage.
- Create comfort zones throughout your home by connecting to select Alexa devices to automatically adjust heating and cooling based on temperature readings or presence detection.
- Save money and energy - After purchase, Amazon will send you an email with details about home thermostat rebates that may be available from energy providers in your area.
- Save energy - According to EPA estimates, ENERGY STAR certified thermostats save an average of $90 on yearly energy bills.
- Programmable thermostat and automatic control - Create your own home, away and sleep schedules, or have Alexa automatically control the temperature with Alexa+ advanced features.
Instead, all you need to do is take off the old thermostat and put a new one on. It’s generally a pretty straightforward repair. Take off the hose and the nuts holding the thermostat on and install the new one!
No matter what you do, never work on your vehicle’s cooling system when the coolant is hot. Wait until everything cools down. If your vehicle just overheated this means waiting at least 24 hours to let everything cool back down.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
How Much Does It Cost to Replace a Thermostat?
While it would cost you at least $100 to have a professional mechanic diagnose and replace your thermostat, if you’re willing to do the work yourself you can save yourself quite a bit of money.
That’s because an aftermarket car thermostat typically only costs between $10 and $30. And since it’s one of the easiest components to replace, there’s no reason you can’t do it yourself and save yourself some money!
A typical car thermostat lasts about ten years, so even if it’s not the right fix the first time you’re not spending a ton and it’s a component you’d need to replace eventually anyway.
Final Thoughts
Now that you know a little more about how your car thermostat and signs that it’s failing, it’s up to you to figure out whether it’s the component you need to replace or not.
If you’re on the fence about whether or not the problem is the thermostat, we recommend replacing it anyway because of how little they cost and how easy they are to replace.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
