Temperature gauge reads high

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.

If you are asking the normal position of the temperature gauge needle in normal operating mode it will be about half way in the gauge reading( between cold and hot). IT may vary about a needle width regardless of the load on the engine and if it climbs up in traffic then you have a problem with the fan operation

If the temp gauge reading is high when the engine is cold it will be a short to the sender unit or a faulty sender unit ( as opposed to a temperature sensor unit). Have the fault codes read to find out what put the engine light on ( overheat)

I'll put my bets on a faulty gage...but that's just me.

Well, it really depends on what temperature the car is when you start it as to which temperature area the gauge reads. Unless you mean that you always start it from the same temperature, yet the gauge reads differently each time.
Is the reading far from average? Is the gauge pointing to wildly differing areas on its scale?

When you said you replaced everything, did that include the temperature sending unit?
The temperature sensor just operates the cooling fan or fans for the radiator.
The temperature sending unit operates the temperature gauge in the dashboard. If that thing is faulty, the gauge won't work right.
If you did change the sending unit, it could be possible that the computor is screwing it up, but in my 41 years as a mechanic I never heard of it, when a computor goes, nothing works.

You may have a blown head gasket, do a compression test.

Find and check the temperature gauge sensor 'sender' unit on the engine.
To test:-
- if you ground the wire connected to the sender the gauge should go to full scale high,
- open circuit the gauge should read zero (nil deflection).
If above test ok, replace the temperature sender unit with correctly specified item.

You need to have a mechanical test gauge hooked up to see if this is a false reading, this special gauge goes into the oil sender tap in the block and will let u know for sure if the pressure is to high cold, if it is the most common issues are wrong weight of oil, do u use oil heavier than 10W-30W? any other oil like 10W-40W will cause high oil pressure readings, the reason is the very tight rod and main bearing clearance's the engines now use, it is only about 1/2 the clearance of older engines, that is so the new fuel saving thin oils can be used.

It may be the thermostat