[Ewoosward]

I have an 03 Honda civic with 200k miles on it, it's my daily driver mostly city driving and I started noticing that the temperature gauge will randomly start to go up saying its overheating but once I turn the heat on in my car it lowers the temperature and then it stays normal

[ma0641]

Make sure the system is properly bled. This is a common problem with air in the system.

[TxGreaseMonkey]

Read your Owner's Manual on how to properly fill the cooling system, in order to prevent air from forming in the system. For instance, you may need to set the heat slide to maximum heat and turn the ignition switch to ON (Position II) to open the heater control valve. This will force any air trapped in the heater core out. Failure to do this properly can blow the head gasket and result in coolant being blown out.

My gut is you need to replace the radiator and properly refill the cooling system with a 50/50 mixture of the proper antifreeze and distilled water. Phosphate scale may be currently blocking passages in the radiator.

[odinn7]

If you haven't touched the cooling system lately and bled the system incorrectly, then you could be facing a bad thermostat, bad cooling fans, crap in the radiator, bad head gasket, or a coolant leak that has allowed your coolant level to get low.

Check your coolant level and go from there.

[Ewoosward]

Thank you very much