The Engine Temp gauge on the dashboard indicates high temperature, just after starting the engine. There are four reasons why the temperature gauge reads high, 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.
Car Troubleshooting
First, check the coolant level of your car, open the hood and locate the coolant reservoir, if you are not sure about the location, refer to your car owners manual. On the reservoir there is a markings that shows the recommended level, the coolant must be in the maximum leve.
Now, check also the coolant level on the radiator, before checking the radiator make sure that the car engine was turned off and the engine was cold, if the engine is hot, let it cools down then 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 causes the Temperature gauge to reads hot. 
However, if the coolant level is high, the 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 collapse hose is preventing the flow of coolant from the radiator to the engine which causes the Temperature gauge to read 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 the 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 keeps 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
(1) Low coolant level
(2) Collapsed radiator hose
(3) Faulty water pump
(4) Faulty thermostat.
How to fix the temperature gauge that reads high after starting
If the problem is a low coolant level, just add the necessary amount of coolant to fixed the problem, a 50/50 antifreeze/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 coolants 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 in 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.
More Engine Troubleshooting Guide
Car Engine Problems Troubleshooting GuideCar troubleshooting guide for common car engine problems based on the technician experience, it will serve as a guide to solve your engine problem, select the article below related to your engine problem.
Learn more: Car Engine Problems Troubleshooting Guide
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