A couple problems

[LJ909]

I have a 13' LT hatch. Auto with the 1.8. Currently at about 122 thousand miles. I have the check engine light on on the dash which Onstar says could be an O2 sensor? My odometer stopped showing up about last year after a new battery was put in, and just recently in the last few weeks the engine overheat light came on twice on 2 separate occasions.

I checked my coolant levels and I have to keep putting coolant in, but I never see any leak, though I can smell when the car has been driven as if there is coolant leaking somewhere. This has also coincided with my heater not getting warm anymore and my air occasionally not blowing that cold.

Could the coolant and overheating issue be tied to me have to keep put coolant in? Also could the computer need a flash from the dealer in order to get the odo to show back up?

 

[Llia]

Do you see coolant puddling anywhere? Other than that you need to check the water pump and the belt if it has not been replaced. Change the thermostat too if it's not a fancy electric one. The heater not working is usually indication of a bad water pump.

Most pumps on other cars I've had go bad will weep a lot of coolant out of a tiny hole near the drive pulley.

 

[LJ909]

Do you see coolant puddling anywhere? Other than that you need to check the water pump and the belt if it has not been replaced. Change the thermostat too if it's not a fancy electric one. The heater not working is usually indication of a bad water pump.

The belts are fine last time I checked. Hadnt even considered the water pump though. But No I never see any coolant puddling anywhere. I just check the coolant tank under hood and its empty. I usually now know its low or empty because I'll hear the engine fan constantly on. But I never see any coolant on the ground, even when I pull out of a parking space, I check on the ground.

 

[Natesriv]

waterpump... I'm betting it's that. You have to get under the car, and look HARD for any signs of green dried or wet coolant. Look for residue. ...
Either the waterpump, or the end of any coolant hose.. leaks not at the ends would be more extreme..
The bane of the early Sonic's....waterpumps...2nd? swaybar end links

 

[LJ909]

waterpump... I'm betting it's that. You have to get under the car, and look HARD for any signs of green dried or wet coolant. Look for residue. ...
Either the waterpump, or the end of any coolant hose.. leaks not at the ends would be more extreme..
The bane of the early Sonic's....waterpumps...2nd? swaybar end links

Im going to have to do that thanks. I didnt know that water pumps were a problem in Sonics. Is it just the 1.8 or the 1.4 as well?

 

[sleepybird09]

Sounds like you have a heater core problem. Since its affecting your heat and can't find any leaks outside. I would check the passenger side floor. And behind the dash. There's a good chance the missing coolant is inside your car.