Temperature gauge reading hot but engine not hot

There could be a few different issues that could cause the temperature gauge on your 2008 Ford Focus to read hot when the engine is not actually overheating. Here are a few things to consider:

Failed thermostat: The thermostat is responsible for regulating the flow of coolant through the engine. If the thermostat is stuck in the closed position, it could cause the temperature gauge to read hot even though the engine is not overheating.

Failed temperature sensor: The temperature sensor sends a signal to the temperature gauge to indicate the engine's temperature. If the temperature sensor is faulty, it could cause the temperature gauge to read hot even though the engine is not overheating.

Wiring issue: If there is a problem with the wiring that connects the temperature sensor to the temperature gauge, it could cause the gauge to read hot even though the engine is not overheating.

To determine the cause of the issue, it may be necessary to perform some diagnostic tests and possibly replace some components. A mechanic or a professional auto repair shop will be able to diagnose the problem and recommend the appropriate repairs. It's also a good idea to keep an eye on the engine temperature and take note of any other symptoms or issues you may be experiencing. This information can help the mechanic diagnose the problem more accurately

Reasons the Temperature Gauge Reads High

If the temperature gauge reads high, it could mean your engine is overheating. Another reason your reading might be high is you could be losing coolant. A small leak or evaporation may cause your radiator to slowly lose coolant. A third reason your temperature gauge reads high could be because the thermostat is broken. If this is the case, you may need a coolant temperature switch replacement. The last reason the temperature gauge could read high is because of a water pump, or water pump gasket failure. If the water pump is malfunctioning, it may need to be replaced by a professional.

What to Do If Your Temperature Gauge is High

If your temperature gauge is reading high, it means your car is overheating. This is a very serious matter and you should never drive an overheating car. If your car starts to overheat, shut off the air conditioner and open the windows immediately. If this does not reduce the overheating, turn on the heater as high as it can go. If this still doesn't work, pull over on the side of the road, turn off the engine, open the hood carefully, and wait until the vehicle cools down. Never open the radiator cap while the engine is hot - coolant can spray and burn you. Once the vehicle has cooled, take the car to a mechanic right away so they can diagnose the problem. Cars are especially susceptible to overheating in hot climates, like what's common in cities like Los Angeles, Phoenix, Las Vegas, or Atlanta.
The temperature gauge is an important tool in your vehicle that shows the temperature of your engine's coolant. Contact YourMechanic and have your car inspected for overheating if it reads too high, as this can cause serious problems...

Reasons the Temperature Gauge Reads Cold

On most vehicles, the temperature gauge reads cold until the engine has run for a few minutes. If the temperature gauge still reads cold after the engine has warmed up, the gauge may simply be broken. Another reason the temperature gauge could read cold is if the thermostat in the vehicle stays open. With the thermostat stuck open, the engine can be overcooled, causing a low temperature reading. If this is the case, the thermostat may need to be replaced.

Wrong gauge for the sensor? Bad gauge?

check that the wire to the temp sender unit has not fallen off and is shorting out on the head/block. The power comes from the ignition switch through the gauge down to the sender unit and because the sender is a temperature controlled resistance unit the voltage is very low and so the gauge reads cold . as the temperature heats up , the resistance is decreased and so the voltage is increased though the gauge and the needle reads higher.. Hench if the gauge goes directly to hot on start up the wire is shorting out or the sender unit is faulty.

If the gauge does not go back to cold when the engine is cold, it could be the gauge on the dash. I am assuming the gas gauge drops with the key off.
You could unplug the temp sensor on the engine to see if it makes any difference.

If your temperature gauge is reading too high, it can only be one of two things: The engine is overheating or the gauge is "lying" to you. I would recommend first taking the temperature of the cylinder head with an infrared thermometer to determine which one it is. If the engine is actually as hot as the guge says it is, then you need to check your cooling system. If the engine is not as hot as the gauge says it is then you need to diagnose and repair your gauge circuit. (most likely an inaccurate temperature sensor)

The temperature sending sensor is bad, it usually goes into the intake area of the engine. It reads hot hot or cold the engine is and this is what makes the gauge work or not work properly. Good Luck

It sounds like the coolant temperature sensor is beginning to fail. It is highly unlikely that the in-dash gauge is a problem. The coolant temp sensor inputs to the computer affecting everything from radiator fan speed, engine fuel/air calibration and a variety of other parameters.

Be absolutely certain to "burp" every bubble of atmosphere from the coolant system too. Air bubbles have the amazing ability to prevent coolant flow and will cause all sorts of problems, especially if the bubble wants to hang around the temperature sensor location.

Normal operating temperature is going to be around 210 F.

Most Autozone, Advance locations will read engine problem codes at no charge, so drop by one of those locations and let them read the problem code.

My guess will be the coolant temperature sensor. Then have the problem code reset, remove all air from the coolant and let us know how this worked.

try replacing your temperature sending switch. That it what tells your gauge or idiot light where to read or light to come on. It may have a short in it. Or a short between the two.

Faulty temperature sensor I think, thats what feeds the gauge. If the vehicle is genuinely running hot there would be a lot of pressure in your radiator causing overflows/steam/coolant smell.
Those sensos wear out and commonly go to short which shows a higher & higher reading until they fully short out
...hope that helps.