daniel42

Hello,

I am new to this forum and I was hoping that someone could help me . I recently purchased a 2004 Honda Civic EX!
Unfortunately, it started overheating and I had to replace the thermostat (wasn't getting heat at times), fan switch (fan was not turning on), and the coolant temperature sensor (just in case).
Now, the car is not overheating, but I noticed that the coolant temperature reaches normal temperatures (~ 1/2 way) when driving in the city, but it drops ( to ~1/4) when driving at highway speeds.
The temperature does rise back to normal temperatures when not in the highway.

Does anyone have an idea what this could be? Also, there is heat (even when the temperature drops).
I read that it could be the thermostat, but I just replaced the thermostat with a OEM Honda part. The fan switch and coolant temperature sensor were aftermarket parts .
Thank you for your help!

Best,
Daniel

TomCat39

Sounds like the thermostat is not closing or the rubber gasket is not present on the new thermostat.

Coolant is constantly flowing through the radiator and on the highway, you get a lot more air flow through the fins.

Also, it is HIGHLY recommended to only use OEM thermostats. Aftermarket thermostats are known to be problematic.

holmesnmanny

https://www.hondapartscheap.com/auto...mp-sensor-scat

exactly what part and number did you swap in and where exactly did you put them in relation to the diagram ?

also it's actually possible sometimes to put the thermostat in backwards in some models, it's rare but something to think about

daniel42

Hello,

It turned out to be that the coolant temperature sensor was faulty (I just placed the old one back in, since it's working just fine). I checked the thermostat and it is opening and closing as it should.
Thank you for your responses!

Best,
Daniel