Honda Repair: 05 Honda Civic check engine light, coolant level, temp gauge

Question
I just bought a used 2005 Honda Civic a few weeks ago. The carfax said it just got new breaks, never been in an accident, two previous owners with 85,000 miles, and I bought it at a reputable dealer.. I was driving it a few days ago when the check engine light came on and it started to heat up slightly. Luckily I was close to home, but on the way back the temperature started to rise and fall in relation to movement. I realize this could be a lot of different things (I checked the gas cap..), but I was wondering if anyone could offer any insight. Thanks!!

-Jade

Answer
The first thing you need to do is check your coolant level. It is likely low. This is a common cause of your temp. gauge acting the way it is. Check it in both the radiator and the coolant reservoir. Check it several days in a row and add if needed.
This could also be a problem with the thermostat.
You need to have your codes checked. There might be something else going on as well and the code that the computer has stored will give you a clue to what else might be going on.