Engine Temperature Sensor Buyer's Guide
- An engine temperature sensor, also known as engine coolant temperature sensor (ECTS) or coolant temperature sensor (CTS) in short, is a small device that can be found in your engine’s cooling system.
- The engine temperature sensor has varying resistance levels for different temperatures that the ECU uses to calculate the necessary adjustments to make across a number of tasks like fuel injecting, fuel-air mixing, and timing the ignition.
- Its exposure to the coolant, as well as coolant leaking to the wiring connectors are two of the common roots of engine temperature sensor problems.
- Bad engine coolant temperature sensor symptoms include: an illuminated check engine light, black smoke, poor fuel economy, and engine overheating.
- OE engine temperature sensor replacements on CarParts.com would cost you around $8 to $55 depending on the brand and series.
The hottest component of your car is the engine because it’s where combustion takes place. Ironically, an engine can’t and won’t function properly if it becomes too hot. To address this, your car is equipped with a number of components to cool the engine and prevent it from stalling or overheating. Collectively known as the cooling system, these components act as your car’s first line of defense against high temperature and they are composed of the radiator, heater core, hoses, water pump, and the coolant.
Most drivers know that the coolant’s main task is to keep the engine cool. However, temperature can vary depending on atmospheric conditions and different driving habits. In order for the cooling system to track the engine temperature at varying outputs, an engine temperature sensor is fitted to ensure that your car is performing at the right temperature.
What is an engine temperature sensor?
An engine temperature sensor, also known as engine coolant temperature sensor (ECTS) or coolant temperature sensor (CTS), is a small device in your engine’s cooling system. It is found along the coolant pipe and works with your vehicle’s electronic control unit (ECU). This monitoring device is responsible for maintaining the engine’s optimum temperature. Designs may vary but it typically looks like a golden or copper bolt with an attached plastic socket head.
What does an engine coolant temperature sensor do?
As the coolant flows in and out of your engine, carrying away and dissipating heat, the ECU carefully keeps track of its temperature. The process starts with the ECU sending a regulated voltage to the ECTS, which then reacts to the coolant’s temperature by means of inputting varying resistance levels. The utilized resistance level is what the ECU uses to determine the actual temperature changes inside the engine. After the successful monitoring, the ECU then calculates the coolant temperature to properly adjust fuel injection and ignition timing. The ECTS is vital in having an accurate reading on the engine temperature gauge on the instrument cluster.
What causes the engine temperature sensor to fail?
The ECTS is constantly exposed to the engine coolant for as long as your car is in operation. Due to this, the device can develop corrosion, which can lead to failure and inaccurate temperature measurements. Another culprit for a failing ECTS is a coolant leak. If the leak happens near the device, it may enter the assembly and damage the wiring connector.
Symptoms of a failing engine temperature sensor
The engine should be working at the right temperature to avoid damage and problems such as engine overheating and misfiring. This is why you always need to make sure that the cooling system is doing its job 100% of the time. Among the devices you need to check is a corroded or malfunctioning engine temperature sensor. Here are the bad engine coolant temperature sensor symptoms you need to be aware of:
Illuminated Check Engine Light
Among the first few symptoms that you could encounter is an illuminated Malfunction Indicator Lamp or Check Engine Light. This is the universal warning for engine issues. It usually turns on without the presence of other symptoms so it’s easy for some drivers to just ignore them. If this light turns on, bring your car to the mechanic to save you from all the worries that may come with it.
A sudden drop in fuel economy
A bad ECTS may fail to send the right resistance for the ECU to read. This would result in poor adjustments in fuel injection, fuel mixture, and ignition timing. Among the things that may suffer is your car’s fuel economy. If your ECU keeps on allowing too rich or too lean fuel-air mixture, the fuel economy will plummet.
Black exhaust gas from the tailpipe
There are a lot of problems you could face if the ECU keeps on sending the wrong signals to your engine due to a failing ECTS. One of them is black smoke from the exhaust pipe, which is a sign that your car has bad emissions. The black smoke is a result of fuel burning in the exhaust system instead of being combusted inside the combustion chambers. This could happen if the mixture is too rich.
A bad engine temperature sensor may send the ECU the wrong signal. If it sends a cold signal despite the coolant being hot, the computer won’t have a choice but to enrich the fuel mixture. If the mixture becomes excessively rich, the engine wouldn’t be able to burn all the fuel inside the chamber. Rather, the unburnt fuel is banished to the exhaust lines.
The exhaust components are normally hot as it is constantly in contact with the exhaust gas. When the unburnt fuel touches the hot walls of these components, it will ignite and cause the black smoke you see as you rev your engine.
As opposed to the black smoke being emitted from the tailpipe, overheating is caused by an excessively lean fuel mixture. If the ECTS sends a hot signal to your ECU, the latter will compensate and give the lean signal to the injectors. If this happens, your engine could overheat easily. You’re also at risk of experiencing engine misfiring and engine ping if you fail to address this problem immediately.
Should you experience one of these symptoms, consider bringing your car to an experienced mechanic. If the engine temperature sensor is the one causing the problem, your only option would be to replace the sensor. Remember that not having bad ETCS once it fails repaired will only put your engine at high risk of developing a serious problem in the future.
How much is an engine temperature sensor?
OE engine temperature sensor replacements on CarParts.com would cost you around $8 to $55 depending on the brand and series. To get the perfect fit, type your vehicle’s year, make, and model in the filter tab under the search menu. You may further customize the list by utilizing the “Refined By” section and choosing from the list of categories like price range, brand, and series.
Selecting an Engine Temperature Sensor for Your Car
Has your car engine been showing signs of poor performance? Has it gone as far as shutting down? Have you noticed a drop in fuel efficiency? A damaged temperature sensor could be the cause of engine overheating. This could also make your car accelerate more slowly than usual. Once you notice these symptoms, it could only mean that it's about time you get your temperature sensor replaced.
What type of engine temperature sensor should be used?
There are two main types of temperature sensor used on automotive engines:
- Negative temperature coefficient (NTC): This type of sensor works in such a way that the internal electrical resistance decreases as it is exposed to more heat. This is the more common temperature sensor type since most automotive temperature sensors are NTC sensors.
It is usually made from different oxides of metals such as iron, cobalt, nickel, copper, and zinc. This sensor is arranged in a potential divider circuit with a permanent resistor. The resistor will be inside the control module to allow the module to measure a variation in voltage or current. Materials with a negative temperature coefficient are used in floor heating.
- Positive temperature coefficient (PTC): This type of sensor works opposite the NTC. The internal electrical resistance increases as it is exposed to heat.
This is usually made from barium titanate. It can be used as a protection device, for overload protection due to the large heating effect from the current flow. When the current flows and the element increases in temperature, its resistance also increases. This has a counter effect and reduces the current flow. This characteristic keeps the PTC from overheating. Materials that have useful engineering applications often show a relatively rapid increase in temperature in PTC.
What are other things to consider when selecting an engine temperature sensor?
Remember that your car comes with a manual, so use it as your guide before you start selecting which type of engine temperature sensor you actually need. For novice DIY-ers, buying a kit is highly recommended since it makes the whole process easier. Make it a point to select only trusted names in the industry since they have been tried and tested and will give you the warranty you need. Though engine temperature sensors are usually affordable, it's still important to find the best fitting replacement for your car. Parts like this, no matter how small they seem, are important for your safety and your engine's performance. By installing a brand-new engine temperature sensor on your own, you'll be able to save money and learn the DIY basics.
5 Steps in Replacing Your Temperature Sensor
The temperature sensor, sometimes called the master sensor, makes sure the engine functions properly by indicating the temperature of the coolant. With a broken temperature sensor, the engine will also malfunction. Read on and find out the 5 steps to replacing your temperature sensor.
Difficulty level: Moderate
Tools that you'll need:
- Set of metric wrenches
- Drip pan
- 1 gallon of antifreeze
- Open end box wrench
- Teflon tape
Step 1: Wait for the engine to cool down to prevent injury. Put the drip pan under the radiator pet-cock. Open and let about 1 gallon of antifreeze drain before closing. Use an open end box end wrench to disconnect the electrical connector on the coolant temperature sensor. If the wire lead has melted and discolored insulation, you will also need to replace the wire lead.
Step 2: Use an appropriate socket and ratchet or open end box wrench to remove the sensor from the engine block. Wrap Teflon tape around the threads of the new coolant temperature sensor.
Step 3: Attach the coolant temperature sensor. Make sure it is tightened enough. Do not torque down on it, or it will distort and not function properly. Next, reconnect the electrical connector on the sensor.
Step 4: Pour antifreeze on the radiator but leave the radiator cap off. Run your car and let it warm up, and wait for the thermostat to open when the radiator reaches 195 degrees F. The fluid in the radiator will decrease. Fill the radiator the rest of the way, and put on the cap. Make sure the overflow bottle is half full.
Step 5: Check the temperature and the electric engine fans to see when they come on (when the temperature gauge shows just over half or at about 215 degrees F.) If they don't come on, then there might be an electrical problem. The coolant temperature sensor might also be faulty or the fans might be damaged.
Replacing your broken temperature sensor can take about 30 minutes to an hour. It won't be so hard as long as you're familiar with your car's specs.