The temperature gauge reads hot after the engine is started. Several reasons are causing this such as the radiator lacks coolant, the hose of the radiator is collapsed, the water pump is faulty, or there is a problem with the thermostat. Possible cause of temperature gauge that reads hot after starting 1) The radiator lacks coolant 2) The radiator hose is collapsed 3) The water pump is faulty 4) The thermostat is faulty The listed reasons above the first two are the easiest to check. Now the first thing to do is to check the radiator if there is enough coolant in the system. Open the hood and locate the radiator, remove the radiator cap. Make sure that the engine is cold before removing the radiator cap otherwise you may burn yourself. Using a flashlight look down at the radiator fill hole to check the coolant level, the coolant level is said to be enough when the coolant covers the fins inside the radiator. If the coolant did not cover the radiator fins then the coolant inside t...