From Ross-Tech Wiki
18613/P2181/008577 - Performance Malfunction in Cooling System
- Check Engine Coolant Temperature Sender (G62)
- Check Coolant Thermostat
- Check Engine Cooling System
- Put the key on, fan speed on 1, and push the a/c switch. Are both fans kicking on? If not, you found the problem.
- Put the key on and fan speed on 1 with temperature set to hot. Does heat come out readily from the vents?
- No. Probably the water pump is gone.
- Yes. Probably the thermostat is gone.