Almost a guarantee that its one of these 2 problems. If it overheats and basically fluctuates in temp, its your head gasket. Ive done this myself, garages will charge about 1K for it, but you can do it yourself in about 3 days - parts$
Second is your thermostat. Simply remove it and replace it. It costs about 30$ at canadian tire or any parts supplier and it simple to remove. just Google for some instructions and photos on where and how to change it.
Honda civic runs on cold bad sign?
The relay is sticking. Replace it.
The 2004 Honda Civic runs on regular unleaded.
The 2009 Honda Civic runs on regular unleaded.
The 2006 Honda Civic runs on regular unleaded.
The 2010 Honda Civic runs on regular unleaded.
The 2003 Honda Civic runs on regular unleaded.
The 2014 Honda Civic runs on regular unleaded.
The 2007 Honda Civic runs on regular unleaded.
The 2011 Honda Civic runs on regular unleaded.
The 2013 Honda Civic runs on regular unleaded.
The 2008 Honda Civic runs on regular unleaded.