The coolant temperature sensor (CTS) is a small component that does a big job as part of your vehicle’s engine management system.
Measuring the temperature of the coolant flowing through the engine, the coolant temperature sensor relays this temperature information to your car’s engine control unit (ECU), which adjusts fuel mixture and ignition timing to ensure your engine runs optimally as well as safely.
In this blog, we’ll take a look at some of the common signs of a bad coolant temperature sensor and explain why they’re worth rectifying.
Topic Summary
- What Are the Signs of A Bad Coolant Temperature Sensor?
- What Happens If A Coolant Level Sensor is Bad?
- How To Fix A Bad Coolant Temperature Sensor?
- How Long Does A Coolant Temperature Sensor Last?
- FAQs on Signs of A Bad Coolant Temperature Sensor
- What Are the Signs of A Bad Coolant Temperature Sensor?
- Can A Bad Coolant Temperature Sensor Cause Engine Overheating?
- Will A Bad Coolant Temperature Sensor Trigger the Check Engine Light?
- How Does A Bad Coolant Temperature Sensor Affect Fuel Economy?
- Can I Drive My Car with A Bad Coolant Temperature Sensor?
- Conclusion
What Are the Signs of A Bad Coolant Temperature Sensor?
A bad coolant temperature sensor has the potential to cause a range of issues that, left unaddressed, can put your engine at serious risk of damage. Some signs of a bad coolant temperature sensor are:
Poor Fuel Economy
Loss is one of the first symptoms of a bad coolant temperature sensor. Since the flywheel is connected to the transmission, the prongs could be hammering on the back of the starter.
When the ECU receives incorrect coolant temperature information from a faulty temperature sender, it might offset the fuel mixture balance, either running too lean or too rich.
Check Engine Light
When a coolant temperature sensor malfunctions, your dash display will feature a check engine light.
Though a host of problems can cause that light, a diagnostic scan tool can often tell you that the issue is with the coolant temperature sensor. Neglecting this warning can lead to more serious problems later on.
Engine Overheating
If the coolant temperature sensor fails, it won’t monitor the engine’s temperature accurately and could cause your engine to overheat.
Overheating can lead to blown head gaskets, warped cylinder heads, or total engine failure. If your temperature gauge is heading into the red zone or steam is coming from inside the hood, get out of the car and check your coolant levels.
Hard Starting or Stalling
A faulty coolant temperature sensor would make starting the engine in cold weather more problematic.
As the ECU adjusts the fuel mixture in reaction to the sensor’s readings, incorrect temperature data will tell the ECU the mixture is richer than it actually is, potentially causing occasional ‘hard’ starts, in which the engine turns over when cranked but fails to fire. Once running, the engine might run roughly or stall.
Black Smoke From the Exhaust
If the coolant sensor malfunctions and gives the computer a too cool reading, then the engine will run too rich, spitting black smoke from the exhaust, telling you that too much fuel is being burned for its intended purpose.
This is not only inefficient but will also foul up the catalytic converter in the long run.
Erratic Temperature Gauge Readings
A bad coolant temperature sensor can make your temperature gauge go haywire, jumping around from normal to hot and then back to normal when there is no real change to the engine temperature.
What Happens If A Coolant Level Sensor is Bad?
A defective coolant temperature sensor sounds like a small problem, but it can quickly snowball into a large one.
If left unaddressed, a faulty coolant temperature sensor can cause your engine to run inefficiently, resulting in poor fuel economy, excess emissions, and potentially overheating, which could lead to serious engine damage that could cost thousands of dollars to fix or, worse, necessitating an engine replacement.
Drive the car too long without coolant, and your car’s engine might overheat and cause significant damage, like a head gasket or warped engine components.
This sensor should be replaced immediately as you might have a faulty coolant level in your car.
If you’re able to catch a bad coolant temperature sensor soon enough, you can save yourself some major headaches later on.
If you experience any one of the symptoms detailed above, take your vehicle to a trained auto technician.
A qualified mechanic can perform diagnostics to figure out the problem, confirm that your coolant temperature sensor is bad, and then, of course, replace it.
How To Fix A Bad Coolant Temperature Sensor?
A bad coolant temperature sensor can cause great harm to the engine. So, before any damage occurs, follow the steps below to fix a bad coolant temperature sensor.
1. Diagnostic Check
The next step is to do a drive cycle diagnostic to determine specifically what is wrong and to see if the coolant temperature sensor is malfunctioning.
2. Sensor Replacement
If the sensor is misfiring, it needs to be replaced. It’s actually a fairly easy task. You find the sensor, usually near the thermostat, take the wiring harness off, pry out the old one, pop in a new thermostat, and reconnect the harness.
3. System Reset
Lastly, following the sensor change, you’ll want to reset the ECU (engine control unit) to clear any error codes your diagnostic scanner has recorded.
Once this has been done, the ECU will begin receiving correct temperature data from the new sensor and adjust the engine parameters to compensate accordingly.
4. Test Drive
Next, take the car out for a short drive to confirm that the new sensor is registering where it should. Keep an eye on the temperature gauge, and look at the check engine light as well.
How Long Does A Coolant Temperature Sensor Last?
Typically, a coolant temperature sensor will last between 100,000 to 150,000 miles for about 8 to 10 years.
Depending on the vehicle type and driving conditions, with extreme temperatures and exposure to coolant leaks or electrical issues causing the durability to vary.
Maintenance check-ups will help to keep the sensor running longer. However, suppose you start to notice any early symptoms of failure gas mileage.
In that case, if your engine runs hotter or your temperature gauge is erratic, get it fixed and replaced to avoid engine performance problems.
FAQs on Signs of A Bad Coolant Temperature Sensor
What Are the Signs of A Bad Coolant Temperature Sensor?
When these occur, common symptoms are poor fuel economy, stalling or hard starting, check engine light coming on, engine running too hot, excess black exhaust smoke, and erratic temperature gauge readings. These symptoms are an indicator that the sensor has provided incorrect data to the driving computer, causing the engine performance issues.
Can A Bad Coolant Temperature Sensor Cause Engine Overheating?
Absolutely, a faulty coolant temperature sensor leads to the engine overheating due to the ECU not getting an accurate temperature reading to allow the engine to regulate the temperature properly as it was designed. Without attention and repair, this condition could lead to engine damage.
Will A Bad Coolant Temperature Sensor Trigger the Check Engine Light?
An erroneous reading from the coolant temperature sensor can set the check engine light: The ECU can’t properly perform its functions if it doesn’t receive accurate data from the coolant temp sensor – and if it doesn’t get the right data, it might set the check engine light to warn you about it.
How Does A Bad Coolant Temperature Sensor Affect Fuel Economy?
This can cause the vehicle to run either too rich that is too much fuel mixed in the air or too lean. That is not enough fuel mixed in the air. Running too much fuel is very inefficient and uses more fuel, running too little fuel uses less fuel. Either scenario will show up as decreased fuel economy and, thus, higher fuel costs.
Can I Drive My Car with A Bad Coolant Temperature Sensor?
Although you could technically drive with it, I wouldn’t recommend driving with a bad coolant temperature sensor. It may cause your engine to overheat, your car to underperform, or use more fuel than necessary. I’d say it’s best to have it checked out and replaced right away.
Conclusion
Though small and often overlooked, the coolant temperature sensor performs an essential function in your engine that affects both its efficiency and safety.
If you fail to pay attention to the signs of a bad coolant temperature sensor, you might end up with a drop in your fuel economy, an overheated engine, and serious engine damage.
Catch the signs of a bad coolant sensor early, and you can keep your vehicle running smoothly without costly repairs.
A malfunctioning coolant sensor will only get worse. If you suspect that your coolant temperature sensor is failing, you should have it checked and replaced by a qualified mechanic.