Troubleshooting car problems of temperature gauge that reads high
Temperature gauge that reads high has four reasons why it happens, the lack of engine coolant, collapse radiator hose, faulty water pump or thermostat. To determine the real cause of the problems, do the car problem diagnosis.
First, check the coolant level of your car. Make sure that the car engine was turned off and the engine was cold, open the radiator cap and look down the radiator fill hole. The coolant should cover the metal fins inside the radiator, if not then the coolant is low and this cause the Temperature gauge to reads hot.
However, if the coolant level is high, next thing to check is the radiator hose. Turn the car engine on and observe the radiator hose, be careful while doing the observation so as not to get injured by a running engine, if you found out that the hose was collapse then obviously this causes the problem. The collapsed hose is preventing the flow of coolant from the radiator to the engine which causes the Temperature gauge reads hot.
But, if the problem is not the hose and the radiator has enough coolant in it then the remaining reason that makes the Temperature gauge reads high after engine has started is a faulty water pump or thermostat.
The water pump is the one that circulates the coolant through the engine and into the radiator. If the water pump is faulty it will not circulate the coolant through your car engine thus making the engine overheat. Same as for the thermostat, it is the one that keep the coolant from reaching the radiator when the engine is cold, but when the engine is warm enough it will allow the coolant from the engine to reach the radiator, if the thermostat is faulty even when the engine is warm enough it will still keep the coolant from reaching the radiator thus the temperature of the coolant inside the engine will keep on increasing until the engine overheat which causes the Temperature gauge reads hot.
Possible cause of temp gauge high reading after starting
Low coolant level, collapsed radiator hose, faulty water pump or thermostat.
How to fix the temperature gauge that reads high after starting
If the problem is low coolant level, just add the necessary amount of coolant to fixed the problem, a 50/50 anti-freeze/water ratio would do. However, it would be better to bring your car to a reputable auto repair shop to determine why the radiator losses a lot of coolant to cause your car engine temperature gauge to reads hot after starting it.
Hence, If the problem is a collapsed radiator hose, just seek out a replacement part on any auto parts store and replace the collapsed radiator hose.
As for the faulty water pump and thermostat, bring your car to a reputable auto repair shop and ask the mechanic to check the water pump and the thermostat to find out which one is causing the temperature gauge to reads hot and replace the problem parts if necessary.