Your car’s dashboard doesn’t just have a speedometer and RPM, there are so many other gauges and warning lights that you should keep an eye on. While driving down the alley, you might have noticed the temperature gauge in your car acting all weird. The temperature needle usually goes up, indicating an overheated engine while sometimes, it could fluctuate also by continuously going up and down.
There could be several reasons behind such an abnormal behaviour and you should take this problem seriously before the damage becomes fatal. If you have recently noticed the temperature gauge going up and down in your car, do not worry. We have all the answers you need and help you troubleshoot the problem.
What Is a Car Temperature Gauge and how does it work?
A car temperature gauge measures the temperature of your engine’s coolant and lets you know if the temperature is normal, or if the engine is overheating. It is either a small analog needle located in the odometer or a digital light that appears only when the coolant’s temperature is low or too high.
The temperature gauge uses a sensor that is programmed to communicate with the car’s thermostat. It senses the temperature and sends an electrical signal to the ECU of the car that corresponds to the coolant’s temperature and displays it via the gauge. This sensor is called a thermistor and is present in all modern cars.
Why Does the Car Temp Gauge Go Up and Down While Driving?
If you’ve recently noticed that the temperature gauge in your car goes up and down while driving, there’s something likely wrong with one of the engine’s components’ let’s take an in-depth look;
1 – Faulty Thermostat valve
A thermostat maintains the engine’s temperature by regulating the flow of coolant through the engine. The thermostat valve is managed by the car’s ECU and allows only a certain amount of coolant to pass at certain times.
It is one of the most frequently moving and functioning parts, prone to damage over time, just like other components. If the thermostat valve remains open, the coolant flows in all the time and lowers the engine temperature, while if it remains closed, the engine would not receive the coolant at all and get overheated.
What you’re experiencing is due to a half-stuck thermostat valve, which lets only a little coolant through. This causes the engine temperature to fluctuate a lot, getting heated and cooled down frequently. This is why the temperature gauge goes up and down while driving.
2 – Radiator Fan Issue
A radiator fan, as the name suggests, is a part of the cooling system of the engine and helps lower the coolant’s temperature after it goes through the engine.
If the radiator fan is lousy or fluctuating a lot, the temperature of the coolant would change and the temperature gauge goes up and down. This is not a costly problem to fix and should be diagnosed at the earliest.
3 – Blown Head Gasket
A head gasket is an important part of the engine, located between the engine block and cylinder head. The function of the head gasket is to ensure the proper flow of oil and coolant through the engine, without them mixing.
Over time and excessive usage, the head gasket can become weak due to wear and negligence and cannot keep the oil and coolant from mixing. When this happens, the performance and fuel economy of the car takes a serious hit, and the temperature of the engine fluctuates a lot. This becomes evident through the temperature gauge needle, which goes up and down frequently.
4 – Faulty Water Pump
A water pump is that component that propels coolant through the radiator into the engine. if the coolant is not replaced on time and the radiator is not flushed during routine maintenance, it can collect debris and get damaged.
A faulty water pump wouldn’t be able to send coolant to the engine properly and the temperature would fluctuate a lot. This will cause the temperature needle to go up and down a lot.
5 – Leaky Radiator
Needless to say that if there’s a leak in the radiator, hose, or pipe, the coolant level would become low. No matter how clean or capable, if not enough, the coolant won’t be able to maintain the temperature of the engine and it would increase frequently.
If your car’s temperature gauge needle is going up and down lately, you should check the cooling system for a possible leak.
6 – Faulty Thermistor
It is highly likely that everything is fine with your engine and that the temperature gauge going up and down is a false alarm. If the thermistor is faulty or has loose wires lying around, it might send faulty signals to the ECU and it shows a frequently fluctuating temperature.
How to fix it
If you notice the temperature gauge needle going up and down, do not keep driving your car. Immediately take it to an expert mechanic and get the fault diagnosed properly. Here’s how you can fix this problem;
1. Replace Thermostat Valve – Repairing this valve is a complex job and might cost more than getting a new one, which is a better option after all.
2. Fix the leak – It could just be a leaky pipe or radiator that’s giving you a headache. So get the system checked and get the leak fixed.
3. Get the Head Gasket Repaired – This is also a complex job and an experienced technician could charge you up to $350 for fixing a blown head gasket
4. Replace Thermistor – A job as simple as replacing a sensor could solve the problem and save you from mental agony. Get the ECU scanned via the OBD-II scanner and fix the error codes.
5. Replace the Water Pump – Replacing the water pump usually fixes this problem and is a better option than trying to fix it, which is usually not successful.
With so much going on under the hood of your car, anything can go wrong and start acting up. No matter how carefully you drive it and how religiously you maintain your car, any small part can become faulty and give you a headache.
If the temperature gauge goes up and down while driving, there could be one of many components that have malfunctioned and should be fixed or replaced immediately. Remember to take your car to a reliable technician and get OEM parts only.
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