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It can be a scary thing when your car’s temperature gauge is rising so you think that it’s overheating. A hot engine is going to cause plenty of problems if not taken care of right away.

In the absolute worst-case scenario, you might find yourself on the side of the road, broken down, with smoke pouring out of your engine. In the best-case scenario, you may only lose some engine performance.

An overheating car can lead to significant internal damage. To proactively avoid these issues, it’s essential to keep an eye on your car’s temperature gauge. But what if the temperature gauge rising but car not overheating?

This article will provide you with all the relevant information on why your car says overheating but not hot, and what to do in this situation!

temperature gauge rising but car not overheating

Table of Contents

Temperature Gauge Rising But Car Not Overheating

The temperature of a vehicle’s coolant system is often indicated by the temperature gauge, providing the driver with a rapid warning regarding the coolant system.

Your engine should be running at a typical temperature of 90 to 105 degrees Celcius (195-220 degrees Fahrenheit), however, most gauges will find it difficult to display this exact temperature.

In general, the temperature gauge should be around the middle and not running hot when the engine is functioning at its regular temperature.

When you start your car and notice that the temperature gauge is higher than normal, you should wait for a few minutes for the engine to warm up before checking the temperature gauge. The typical temperature for your engine will be wherever the temperature gauge is, though this may not always be accurate.

Some cars have their temperature gauges wired differently than others. Most modern-day vehicles use an engine control unit (ECU) that uses the coolant temperature to calculate the proper air-fuel mixture at various temperatures.

The coolant temperature sensor’s wires first go to the engine control unit, and then the information is relayed to the cluster. While in other vehicles, the coolant temperature sensor’s two wires go straight to the cluster. The engine control unit is commonly absent in cars that use coolant temperature as information.

Why Is Temperature Gauge High but Car Not Overheating?

Ever wondered why my temperature gauge is high but car not overheating? There will be a number of possible causes for your car temperature gauge hot but not overheating.

If there’s an issue with the temperature of the temperature gauge, it is likely to be due to any of the following reasons:

  • Temperature sensor failure
  • Broken temperature gauge
  • Engine control unit failure
  • Corrosion in connectors
  • Damaged sensor or gauge wires
  • Insufficient coolant or air in the system
  • Head gasket failure
  • Faulty water pump
  • Overheating engine
  • Overused engine

Let’s take a look at each in more detail!

Temperature Sensor Failure

The temperature sensor’s role is to determine the engine’s temperature. If your temperature gauge reads hot but engine cool, it’s likely that you are getting a false measurement. This implies that the temperature sensor is failing or has malfunctioned.

A malfunctioning temperature sensor not sending out correct readings, may lead to the car responding by displaying a misleadingly high temperature on the temperature gauge. It’s rather easy for the sensor to become stuck or impaired by debris when driving.

In addition to this, if the sensor’s connections become destroyed, the sensor will be ruined and won’t be able to send out accurate information. Clean and inspect your temperature sensor if you get false high-temperature readings.

Broken Temperature Gauge

If the temperature gauge is broken, the car will not be able to accurately tell you when it is too hot. When the temperature gauge breaks, the needle can shatter and become stuck in a certain position. So, it may be that the reason your temperature gauge reads hot all the time is that it has become stuck due to damage or even grease.

The needle may need to be repaired if it has broken, which can be done at your local car garage. The sensor itself may be broken and will need to be completely replaced.


Engine Control Unit Failure

If the engine control unit fails, it’s possible that the temperature gauge hot but not overheating. Although this is a rare incident, it will result in the temperature gauge receiving incorrect data from the ECU, which sends data to the cluster.

You can use an OBD2 scanner to double-check and look for any fault codes that give temperature data. If the temperature measurement in the engine control unit is different compared to the temperature reading in the cluster, you must make sure they’re both using the same sensor.

A professional mechanic will need to check this so that the correct steps can be taken.

Connector Corrosion

Corrosion can be at fault for the wrong temperature being recorded by the sensors and sent to the temperature gauge. You will likely find corrosion in the connectors at the sensor, the cluster, and maybe even the engine control unit.

You will need to clean the spray and the connectors using something like brake fluid. If you discover corrosion on any component, it’s likely that you will need to have this component fixed because it has become worn.

Damaged Sensor or Gauge Wires

Faulty wires connected to the temperature sensor or temperature gauge can cause the temperature gauge rising but car not overheating.

The wires can be run straight from the sensor to the cluster or to the engine control unit and then the cluster. You should therefore inspect these two components for any damaged wires.

Insufficient Coolant or Air in the System

If the engine has insufficient coolant or air in the system, your temperature gauge reads hot all the time. If your gauge is reading hot, double-check that your engine isn’t overheating. 

Make sure you have sufficient coolant in the system and that no air has got into the system when you are changing the coolant.

Head Gasket Failure

The head gasket seals key components like the coolant, combustion chamber, and engine oil pass. It’s likely that your car’s temperature gauge will rise if you have a leaky head gasket.

The head gasket creates a seal between the engine block and the cylinder head, and therefore, is an important part of your car engine. Any damage to the head gasket might cause serious problems with your vehicle.

Faulty Water Pump

The water pump is an important part of any car’s cooling system. The coolant is pushed throughout the cooling system with the help of the water pump. The water pump can fail, resulting in a lack of coolant flow which may result in a temperature gauge high but car not overheating.

A water pump can fail for a variety of reasons, which includes:

  • Breakage of the shaft
  • Seal leakage
  • Casting damage

Overheating Engine

If your car temp gauge reads hot when cold, it could be because you aren’t aware of the engine actually overheating. Low coolant or oil are the likely causes for an engine to overheat.

Continuing to drive while your vehicle is overheating might cause the engine to wear out faster, reducing its lifespan and damaging components further. Be vigorous when checking if your engine is overheating or not.


Overused Engine

If the engine has been overused or overworked, temperature gauge hot but not overheating. If you’ve been driving for too long, on rocky terrain, or if you’ve been accelerating for a long time, the engine can become overworked and send signals to your temperature sensor.

It is best to come to a complete stop and allow the engine time to rest in this situation. After the engine has rested, you can resume driving if the vehicle is not hot.

When Do You Need to Fix Your Temperature Gauge?

If your temperature gauge is broken, you’ll receive false readings indicating the temperature gauge high but car not overheating. It’s very important that you figure out why this is occurring and then get it fixed as soon as possible.

If you discover that your temperature gauge is increasing and giving you inaccurate readings which tell that your car overheating but it’s actually not, it’s probably time to replace the temperature gauge.

It may only need repairing at your local garage. The needle might stay in the same spot for several minutes and won’t move out of the red zone, indicating the gauge is probably broken.

Another clue that it needs to get fixed is if the temperature reading stays between 25 and 35 degrees Celcius after starting your car driving. Or your car’s mileage begins to rapidly fall.

I recommended examining the radiator cap and seeing if it is or isn’t properly closed. If it’s the latter, the temperature indicator might display an inaccurate reading.

Finally, if you’re driving slowly or idle, and the temperature gauge changes from normal to cold then this is an indicator that the temperature gauge is damaged and will need repairing or replacing.


Fixing Temperature Gauge Rising but Car Not Overheating

If your car’s temperature gauge is rising but your car is not overheating while you’re driving, there’s a problem. A stuck thermostat or a cooling fan that isn’t working properly could be the cause of your car’s temperature gauge doing this.

The flow of coolant in your car’s engine is typically controlled by the thermostat. When your thermostat isn’t working properly or is stuck closed, it will prevent coolant from flowing properly through your engine.

As a result of this, your engine temperature may change or remain hot. On the other hand, if the thermostat is jammed open, the coolant might circulate regularly, causing the motor to fail to reach its proper operating temperature.

The cooling fans could be running irregularly due to a faulty cooling fan relay or its resistor. If the fan relay fails, the fan might turn on randomly, stay on all the time, or not turn on at all, which can dramatically affect the engine’s temperature. The resistor, on the other hand, controls the stages at which the fans turn on.

To be able to remedy this problem, you will need to consult your car’s user’s manual/handbook. You may be required to ground the wire that connects to the temperature sending unit, however, it’s important to note, that grounding the wire might cause harm to the temperature gauge.

Driving at the correct engine temperature is critical. If you’re having an issue with the temperature gauge rising but car not overheating, you can use a professional OBD2 scanner to thoroughly diagnose this problem.

When an issue like this occurs in a car, an error code is communicated to the diagnostics unit and is recorded there. The OBD2 scanner will allow you to display the problem code stores within the unit.

How Can You Fix Temperature Gauge High but Car Not Overheating?

  1. If the check engine light is lit up, you should first look for diagnostic trouble codes which could lead to the origin of the problem.
  2. Before unplugging cables, make sure the ignition switch is turned off. Then, to avoid damaging the computer, turn the ignition switch on to check the gauge or warning light response.
  3. Turn the ignition off and unplug the electrical connector for the sending unit. Then press the “On” button on the ignition switch.
  4. Whether the engine is warmed up or chilly, the gauge should read cold. You can now ground the signal line with a jumper wire, then turn the ignition switch “On.” and it should say “hot” on the gauge.
  5. If the temperature gauge reads anything other than “cold” when you unplug the sending unit, you should unplug the wire at the temperature gauge as it is likely shorted.
  6. If the gauge still then reads higher than “cold”, you will likely need to replace the gauge.
  7. Finally, check the circuit fuse again if the gauge does not read “hot” when the wire is grounded. If everything appears to be in order, ground the gauge terminal where the wire attaches. If the gauge reads “hot” you’ll need to inspect the wire for any signs of damage.

What Should You Do If Your Car Is Actually Running Hot?

Well, what if your car’s temperature gauge is high and the car is actually overheating? You should immediately pull over to the side of the road and inspect what’s going on.

If the engine is seriously overheated and you weren’t aware of it, you could experience some serious internal damage. After pulling over, make sure the air conditioner is turned off and the windows are open.

Once you’ve stopped running the engine and other equipment in the car, check the temperature gauge to see whether it starts to drop. If it doesn’t drop after several minutes have passed, you will likely need to visit your local car mechanic to have the issue diagnosed.

How to Prevent Your Car From Running Hot

There are a number of measures you can take to help prevent your car from running hot and causing internal damage to key components.

Monitor Temperature Gauge

The temperature gauge is generally mounted on the dashboard, and has a needle that should always be pointing toward the centre. Monitor the temperature gauge and if the car becomes heated (gauge moving up), it’s best to pull over, turn off the engine and let it cool down before it overheats too much and causes damage. This is a simple preventative action to take.

Fill the Engine With Sufficient Coolant

Filling the engine with sufficient levels of coolant is particularly critical during the summer months. You should open the hood and look for the coolant reservoir to check the coolant level.

On the reservoir, there will be lines that indicate the coolant level. If the coolant level is too low, simply add more coolant.

50/50 mixtures of water and coolant are commonly sold as engine coolant. But, you can also purchase concentrated coolant and make your own water-coolant mixture.

It’s important to never add coolant to a hot engine as a precaution. You should always let the engine cool down before removing the cap or pouring in the coolant.

Flush the Radiator

You may need to get a professional mechanic to conduct this step for you. A radiator flush, also referred to as a coolant flush, typically consists of draining the old coolant from the radiator, cleaning the radiator using flush fluid, and then refilling it with a new coolant.

Even if you maintain proper engine coolant levels, you will eventually require a flush due to the coolant becoming unclean.

Professional mechanics recommend flushing on average every 40,000 miles, but you should refer to the manufacturer’s recommendations in your owner’s handbook for exact recommendations for your vehicle.

Consider Changing Car Battery

Your car battery may not be producing the same amount of power as it previously was, and if this is the case it may be forcing your car to work harder than it should, and therefore overheating.

A professional mechanic will be able to help you figure out whether you require a new battery or not.

Parking Car in Shade & Using Window Blinds

There is a significant temperature difference between the shade and the sun and this can not only be felt by you, but also by your car. Parking in the shade will not only keep you cool, but it will also help your car last longer.

If you can’t find a shady spot to park in, you could opt for purchasing a shade to place inside the windscreens of the car to reduce the heat.

Window shades, or blinds, in your car are fantastic options because you can’t always rely on finding a shaded or covered parking spot. These UV heat shields will keep your interior cool while also shielding it from any potential UV radiation damage.

Tinting Windows & Leaving Them Open

Window tinting, or window film, can be applied by a local car mechanic or auto body shop to help keep your car cooler and protect it from incoming UV rays.

Hot air is also trapped behind closed windows, and the glass will work as a conductor, causing the enclosed room to heat up. Therefore, you can allow the hot air to leave by gently opening your windows.

Utilizing AC

To utilize your AC, most people will hop in their car and crank the vents on “high.” However, it is recommended to direct the air through the floor vents.

As you will already know, hot air rises, so the trick is to turn on the bottom vents on the highest setting on your blower to blast it out. Once the car has begun to cool, the upper vents can be opened to better circulate the air.

You should turn on the fresh air setting on your air conditioner for about 10 minutes. When you’re using the recirculation option, you’re just moving around the hot, trapped air around your vehicle.

FAQs (Frequently Asked Questions)

Why is my car temperature going up but not overheating?

Your car temperature going up but not overheating can be caused by a damaged radiator, low-quality or insufficient coolant, a damaged radiator cap, a faulty radiator fan, or simply a damaged thermostat.

Why is my temperature gauge going up and down but not overheating?

The most common reasons for your car temperature gauge going up but not overheating are due to temperature sensor failure,
a broken temperature gauge, engine control unit failure, corrosion in connectors, or damaged wires feeding to the sensor or gauge. All of these reasons can lead to misinformation being displayed on the temperature gauge.

What causes a car’s temperature gauge to rise?

The main problem as to why your car’s temperature gauge is rising will lie within your car’s cooling system. It could be anything from faulty wiring to the fact that the temperature gauge is worn out and needs to be replaced. It could also be due to a bad coolant temperature sensor (CTS) sending the wrong information. You will need to narrow down the possible causes, diagnose the problem, and fix it.