First things first. The original post says the temp gauge is reading hot. It doesn't say that coolant is boiling over or that there is loss of coolant. Also, 2 blocks distance is not sufficient time to overheat if the water is circulating unless the car has sat at idle for quite a few minutes time prior to driving. So….
A) Determine if the sytem is overheating or is the gauge faulty.
1) Is there any loss of coolant when the temp is high?
Are either or both of the radiator hoses hot when the temp gauge says high temp? If the hoses are not hot there is likely no coolant flow.
2) Check for coolant flow by removing the thermostat, and running the engine with the radiator cap removed. If there is flow the pump is likely good.
3) With the radiator cap removed examine the coolant. Are there bubbles in the coolant. If so it would indicate that there is a blown head gasket.
4) Remove the temp sender and place it in boiling (or as close to boiling as possible) water while powered up and connected to the car. Does the gauge read correctly?
If you have already done these basic checks then disregard.
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