If your car is overheating it can be due to many things
When people hear 7mgte... they immediately think they have a blown head gasket.. this is not always the case
it's a good idea to run through a few other things before you think the worst
overheating generally only happens when stopped in traffic, on the highway the temp comes back down but here's a few things to check anyhow
check your water pump
your viscous fan
make sure your thermostat is opening properly (if in doubt, just buy another one they're only $15odd nzd)
make sure your radiator isn't blocked
check for any split hoses
check for any water leaks
your heater core might have air bubbles in it so you need to burp your cooling system (best way i found is jack her up so the radiator is at the highest point... make sure the engine is warm at this point and start her, get the hose or bottles of water and start topping her up... she might bubble a bit while air locks are being cleared, once the bubbles stop cap her up and set her back on the ground)
if none of this has solved your problem get a "TK head check" and check for exhaust gasses in the cooling system... if the blue liquid changes to a greeny colour then it's possible there's exhaust gasses in the water, if it turns yellow there's a definite sign you have exhaust gasses ( i think thats the right colours... it will say so on the instructions anyhow )
if it does confirm exhaust gasses in your water you have absolutely blown your head gasket so get ready to pay out :P
also check your oil, make sure it's not discoloured at all.. milky or chocolate milkshake... if this is the case... you have blown your head gasket or you may have a crack in the block or head... you need to strip her down and get the engine reconditioner to check this for you... usually you can tell by looking at the head gasket.. if the head gasket has definite signs of blowing between galleries usually you don't need to worry bout cracks but you still need to get it all checked.... last thing you want is to buy all the parts, slap her together only to have it happen again
well that's all i have to add for now.... anyone else like to add