The Drive and its partners may earn a commission if you purchase a product through one of our links. Read more.

So your car’s temperature gauge is acting up, or not working at all, and you want to fix it? Good for you. Your car’s engine temperature is vital to its operation, and a properly-operating gauge is a window to its health. Plus, it could mean the difference between getting to work and being stranded in a deserted mining town as zombies size up your brain. Anyway...

In modern cars, the temperature gauge also helps the engine computer set a proper fuel-to-air mixture. That's important for both fuel economy and engine longevity. But figuring out what’s causing your temperature gauge to fail, or behave erratically, isn’t just a case of “here’s what’s wrong.” It will likely take some troubleshooting. The Drive’s crack How-To team is here to help you diagnose and fix your temperature gauge, and get back on the road.

Estimated Time Needed: One hour or more

Working on your car can be messy, especially when you’re working with surfaces you’ve never bothered to clean before. It can also be dangerous as liquids can be scaldingly hot and parts could fall on your toes. So here’s what you’ll need to ensure you keep your jeans, shirt, and skin spotless, and your bones fully intact.

Organizing your tools and gear so everything is easily reachable will save precious minutes waiting for your handy-dandy child or four-legged helper to bring you the sandpaper or blowtorch. (You won't need a blowtorch for this job. Please don’t have your kid hand you a blowtorch—Ed.)

You’ll also need a flat workspace, such as a garage floor, driveway, or street parking, though check your local laws to make sure you’re not violating any codes when using the street.

We’re not psychic, nor are we snooping through your toolbox or garage, so here’s what you’ll need to get the job done. 

The most common cause of faulty temperature readings is a broken coolant temperature sensor (CTS). The part, which is normally located near a vehicle’s thermostat near the base of the radiator (consult your owner’s manual or repair guide) can get gunked up and fail. 

The second most common fault is a bad thermostat. This little part manages the flow of coolant from the radiator to and from the engine and can become stuck open or closed. Neither is a good thing for your engine. The thermostat is usually located at the top of the radiator or at its base (consult your owner’s manual or repair guide). The only way to test a thermostat is by removing it completely and submerging it in a bucket of hot water to see if it opens. Here’s how to test and replace a faulty thermostat.

Another common reason for a faulty temperature gauge is air making its way into the radiator hoses. Air can pool near the temperature sensor or the thermostat and cause faulty readings (or no readings at all). It can also affect the car’s overall cooling efficiency. Here’s how to diagnose and to fix air in your hoses.

The average DIY’er may need a professional to diagnose and fix a faulty instrument cluster. If you’ve already checked the three possible culprits above and none were the cause, it’s more likely something is wrong with the gauge cluster itself. 

Here are our top pro tips to help you diagnose and fix your temperature gauge.

Since you may not have access to the right tools, we also compiled a list of our best hacks to make your life easier and drain your pocket less.

Automakers build these parts to survive and often you won’t know it’s time to replace one until it fails.

About every 30,000 miles or every third oil change for most modern cars.

Evans High-Performance Waterless Engine Coolant

K-Seal Multi-Purpose One Step Permanent Coolant Leak Repair

Got a question? Got a pro tip? Send us a note: guidesandgear@thedrive.com

Sign Up For Our Newsletter

Technology, performance and design delivered to your inbox.

© 2022 Recurrent Ventures. All Rights Reserved.

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.