Hello everyone,

For some days now, I noticed my car's(Honda civic 2003) coolant drains after a while. both coolants in the rad and reservoir are totally drained without any visible leak. I have changed the RAD cap twice but the problem still persists. I did a scan and got P0128 thermostat error. Could this be the problem?

 

check for signs of coolant behind the engine, inside your car near the front under the dash. start there

 

I have done this, no noticeable leak anywhere. Thinking maybe i should just change the whole radiator setup.

 

compression test, if good then pressurize cooling system and look for leak