Thursday, January 22, 2015

DIY: Replacing the Engine Thermo Switch

Inspecting for leaks, check. Cleaning the dirty radiator, check. Removing a busted thermostat, check. After all that shebang, Ace is still overheating. I know, right? There was a moment there that I wanted to jump off a cliff. But finally, we figured out what the heck is wrong with my cooling system. Drum roll please... its was all caused by an itty-bitty thing called the Thermo Switch.

"A thermo switch sometimes called a fan switch is a temperature sensor. Usually close to the radiator in your vehicle engine this device is the one that switches on the fan as soon as the engine/ radiator reaches a set temperature." -

I can't believe it was staring us in the face the entire time. I had no idea about thermo switches until that day but why didn't I check the fan? We tested it and confirmed that the right radiator fan really wasn't turning on. A total facepalm moment.

So anyway, I was surprised to find out how easy it is to replace a thermo switch so I went ahead and tried it myself. Didn't have my nails done yet so it's perfect timing for a DIY session. :)

  • A brand new thermo switch (of course)
  • 24-inch open wrench
  • A glass of soda and chips to reward yourself when you're done.


Step 1. In a Honda Accord, the thermo switch is right beside the air intake as seen here where the cute little pink arrow is pointing. First step is to remove that socket that's connected to the radiator fan.

Step 2. Whip out your 24-inch wrench and start working it loose. If you notice I removed the air intake assembly so I could get more access to it. Totally your call if you want to remove yours.

Step 3. Aaand it's out! Take the time to appreciate it's beauty. Or in my case, cuss on it like crazy.

This is how it looks like with the thermo switch removed. You can see the housing filled with water because it monitors the water temperature in the engine.

Step 4. Bust out your new thermo switch and put it in there. Make sure it's nice and snug.
Needless to say, the left one is brand new. I wanted to get an OEM thermo switch but the nearest auto-supply only carries replacement parts. This Tama thermo switch costs only Php 650.00. It's made in Japan so it's worth a try. Cheaper too, of course. A Honda thermo switch would be around Php 1,300.00. Let's see how long this lasts.
Step 5. Connect the fan socket again and you're done! Pat yourself on the back.

Step 6. Sit back and get that bag of chips and soda. Good job, you!

After replacing the thermo switch, the right radiator fan was finally turning on at the right temp. No wonder I was overheating. With that busted thermo switch my radiator fan won't turn on. Hence, the overheating. Ace now has a healthy cooling system! Yey!

Mystery. Freaking. Solved. :)  


  1. GOOD JOB!!! pero in case na abutan ka sa daan and there is no mechanic to help you at nasira ulet thermoswitch mo, pwede mo i-rekta na lng para once na you turn ON your engine eh naka bukas na agad ung radiator fan mo. . . para lng makauwe ka at madala mo sa isang mechanic or auto supply pra mapalitan mo thermoswitch. . .

  2. Nice job! I would never do this, perhaps if it will be broke I will know what to do, thanks to you! Actually I also start to understand how it arranged inside of the vehicle. When I was buying my first car, I should to learn it well, to avoid buying the garbage. First what I did after reading advices, I checkedthe VIN code of choosen car befor the purchase. Using this online service i got the reports about cars in two min, which allowed to me, to decide between models, and pushed me to the right decision. Today I'm an owner of Honda crx, my lovely red rocket. I love the old cars, they much intresting, at least they looks like a real car, unlike identical new machines from the conveyor, which inside have nothing but plastic


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