Why Jeep Wrangler Temperature Gauge Fluctuates: Reasons?

A temperature gauge plays an essential role in managing the engine’s temperature. But a defective temperature gauge fails to keep up with an immediate response from the engine. So, what are the possible reasons a jeep wrangler temperature gauge fluctuates?

The significant reasons for temperature gauge fluctuation are a damaged thermostat, broken cylinder head gasket, defective cooling system, radiator fan failure, and a flawed temperature gauge. 

In addition, symptoms like extra fuel consumption, wrong temperature reading, and black fume from the tailpipe confirm this issue.

It’s pretty easy to fix the faulty temperature gauge. However, you must confirm the issue before finding a solution for the particular engine part. A mechanic works like an extra helping hand while fixing the faulty temperature gauge.

Possible Reasons Behind Jeep Wrangler Temperature Gauge Fluctuation

“Temperature gauge fluctuation” is a problem directly related to vehicle engine parts and is not the same as climate control problems. There are several reasons responsible for temperature gauge fluctuation.

These causes are sometimes related to sensitive engine parts, and occasionally simple defective parts cause instability. It helps a newbie detect the signs of a faulty temperature gauge if he knows the reasons behind the failure.

Defective Thermostat

A thermostat monitors the engine temperature and balances it between 180 degrees Fahrenheit to 200 degrees Fahrenheit. The thermostat opens the coolant path for coolant to reach the engine when the engine comes to the maximum temperature.

A stuck thermostat doesn’t allow coolant to enter the engine when the temperature reaches 200 degrees Fahrenheit. It results in overheating and leads to engine failure.

On the other hand, the stuck-open thermostat does the opposite. It lets coolant enter the engine before it gains maximum temperature. As a result, the engine decays faster, and the temperature gauge always stays cool.

Damaged Cooling System

Trapped air inside the engine cooling system is a prime reason behind a faulty temperature gauge. Air caught inside the radiator makes a bubbling sound similar to a waterfall.

Damaged Cooling System

Despite having a bubble removal system, wranglers fail to remove bubbles from their engine—consequently, the temperature rises, which is responsible for temperature gauges’ fluctuation.

Moreover, if you find piston slap or rod knock issues with temperature gauge problems in your jeep, it also indicates your jeep engine is facing trouble, and you should take care of it.

Dripping Cylinder Head Gasket

A dripping cylinder head gasket occurs when the engine is overheated. A leaking head gasket fails to separate the coolant and oil. 

Dripping Cylinder Head Gasket

It leads to a coolant-oil mixture that fails to lubricate the machine properly. Improper lubricating of the engine pilots to engine failure.

Broken Temperature Gauge

A broken temperature gauge is the ultimate reason for a fluctuating temperature gauge. It can be a manufacturer’s fault in a new car. 

Broken Temperature Gauge

But it’s a serious problem both in new and old cars. A defective temperature sensor can’t function properly, resulting in a damaged temperature gauge.

Radiator Fan Failure

The radiator fan adjusts the engine temperature to reduce overheating chances of the car’s engine. However, a damaged radiator fan can’t cool off the machine properly. As a result, it leads to engine overheating, possibly an engine failure.

Installing a new radiator fan is the only solution to fix the temperature gauge’s imbalance movement.

Signs Of A Damaged Temperature Gauge

The sign of a broken temperature sensor is pretty common to other engine problems. So, don’t be afraid if you mix it up with other engine problems. 

Knowing the signs of a damaged temperature gauge enhances the chances of finding a solution. So take a quick look at these symptoms to confirm if it’s a temperature gauge-related issue.

Inaccurate Temperature Reading

It’s the first and the most common sign of a faulty temperature gauge. You’ll observe that the temperature gauge jumps up even if the engine isn’t overheated. However, it may be the opposite when it is overheated.

A faulty water pump and jammed radiator can increase the inaccurate temperature reading chance in the car. Sometimes the temperature exceeds the normal range. As a result, the ECM fails to detect the fault.

Acute Polarities

The temperature gauge gets too hot or cold, having a huge gap with the engine’s temperature. You can confirm the temperature gauge has broken by comparing the engine’s temperature with the gauge’s reading.

Loose wirings, rusty sensors, polluted coolant, and a damaged ECU increases the polarity chances.

Check Engine Light ON

Sometimes new drivers become confused when they find the traction control light on or the engine light on though two lights serve in different ways. An illuminated check engine light is the universal problem indicator.

Check Engine Light ON

It’s pretty common to confuse various engine problems when your check engine light is ON is easy. Use an OBD-II or DBM-II scanner to confirm if it’s related to the DTC code. Otherwise, you can be sure your temperature gauge is broken.

Consuming Extra Fuel

Well, you’ve to be a pro driver to confirm a faulty temperature gauge by observing your car’s fuel consumption. A damaged ECT (Engine Coolant Temperature) Sensor sends the wrong signal to the PCM.

Consequently, it results in an inaccurate air-fuel combination leading to extra fuel consumption. You can easily detect it when you are not getting better gas or fuel mileage in your jeep.

Starting Problems

Since a defective temperature gauge leads to the wrong fuel-air mixture, it becomes difficult to start the car. Sometimes, the vehicle won’t start at all. 

Therefore, you must look through all the problems relating to starting problems before fixing the lousy temperature gauge.

Failing Cooling Fans

Cooling fans use a Thermo-switch supported by a DC electric motor to cool off the engine. But a compromised temperature sensor means a faulty ECT sensor. Eventually, it leads to a bad fuel mixture.

As a result, the cooling fans fail to operate optimally because of an inadequate fuel mixture.


Engine failure is unavoidable when the cooling fans aren’t working. The ECU receives wrong signals from the engine resulting in engine overheating. 

It’s a common issue in vehicles sharing the same ECT sensor for the cooling fans.

Black Fume

Your vehicle’s temperature gauge is damaged if you see black smoke coming from the tailpipe. Black smoke appears when the faulty temperature gauge is left unchecked. It also means high fuel consumption and incorrect signals to the car’s PCM.

Imbalance Vibration

You’ll face engine power loss because a temperature gauge can affect the crucial parts of the engine. Since a malfunctioned temperature gauge can’t determine the correct fuel-air ratio, the motor vibrates differently.

Possible Fixes For A Broken Jeep Wrangler Temperature Gauge

Don’t be afraid if your car’s temperature has gone bad. Take an expert motorist’s help before you DIY to solve this problem. 

Follow the guideline below to fix the temperature gauge issue yourself.

Install New Thermostat

First, locate the thermostat unit. Then, use a bucket to collect the coolant from the thermostat. Remove the old thermostat after clearing the coolant. 

Remember to remove the old hose before installing the new thermostat. Lastly, inspect the coolant height.

Change Coolant Temperature Sensor

You’ll find the coolant temperature sensor near the thermostat. But it differs depending on the car’s make and model. 

Next, put a bucket below the sensor. Remove the connector pin from the old one and compare it to match it with the new one.

Now, detach the old sensor with a ratchet. Then, Fix up the new sensor tightly ASAP. Next, attach the connector pin and check the coolant level after you’ve put it back.


A fluctuating temperature gauge fails to deliver the correct message to the vehicle’s ECU. Engine failure is the worst outcome of a nasty temperature gauge. It is ultimately costing you a fat fixing sum for the engine.

Most of the time, drivers and owners ignore temperature gauge issues as their vehicle is serving well.  But, the truth is that it’s leading your jeep into a crisis from oil leaking to voltage regulator problems.  So, when your jeep wrangler temperature gauge fluctuates, take all steps we have just said in this article as soon as possible.

We hope you’ve found the answers to the topic related to the fluctuation of your car’s temperature gauge. First, inspect the failing signs properly to confirm the gauge problem. Then, remember to take your vehicle to an expert mechanic for better service.

Scroll to Top