Exhaust temp sensor

Types of Exhaust Temp Sensors

An exhaust temp sensor measures the temperature of the exhaust gases coming from the engine. It helps the engine control unit (ECU) optimize the air-fuel mixture and track the health of the catalytic converter. The Exhaust gas temperature (EGT) sensor is essential for controlling emissions and improving engine performance.

There are three main types of exhaust temp sensors, namely:

• Thermocouple

  It consists of two different metals joined at one end to form a junction. When the junction experiences temperature changes, it generates a small voltage. The voltage difference is measured and used to determine the temperature of the exhaust gases. The temperature difference between the two ends of the thermocouple produces a voltage signal that indicates the temperature of the exhaust gases.

• Thermistor

  It's a resistor made from ceramic materials with a negative temperature coefficient. Exhaust temperatures affect its resistance. When the resistance value is measured, it can be used to determine the temperature of the exhaust gases. The change in resistance of the thermistor is used to calculate the temperature of the exhaust gases.

• Resistance Temperature Detector (RTD)

  It is an accurate and stable temperature sensor. It consists of a coil of pure platinum wire. The coil's resistance changes in a predictable way with temperature. An external power supply passes a current through the coil, and a measurement device monitors the resistance. The change in resistance is used to calculate the temperature of the exhaust gases. The RTD provides precise measurements of exhaust temperatures but is more expensive than other sensor types.

Specification and Maintenance of Exhaust Temp Sensor

Different models of exhaust temperature sensors have distinct specifications that suit various applications. Here are some general specifications of EGT sensors:

• Measuring Range

  Each sensor has a specific measuring range that indicates the lowest and highest temperatures it can accurately record. The measuring range is vital as it helps choose the right exhaust temperature sensor for a given application. Generally, the measuring range is between 0-1000 degrees Celsius.

• Response Time

  Response time refers to the duration the sensor takes to detect a temperature change and reflect it on the display. The response time is essential for applications where temperature changes occur rapidly and need instant detection. Exhaust temperature sensors with a short response time are ideal for such cases.

• Accuracy

  Accuracy is a critical specification for exhaust temperature sensors. It shows how precise the sensor is while measuring temperature. High accuracy levels provide reliable and consistent temperature readings. Some exhaust temperature sensors have an accuracy of ±1 degree Celsius.

• Material

  Material is also an important specification of exhaust temperature sensors. Different sensors are made from various materials suitable for measuring temperature in harsh conditions like high pressure and extreme heat. Common materials include steel, Inconel, and titanium.

• Diameter

  Every exhaust temperature sensor has a specific diameter. The diameter is an important specification because it determines how the sensor fits in different applications. Some sensors have a diameter of a few millimeters, while others are several centimeters wide.

When an exhaust temperature sensor is well taken care of, it can last long and give accurate readings. Here are some general maintenance tips:

• 1. Proper installation of the exhaust temperature sensor is the first step to easy maintenance. Make sure that the sensor is securely mounted and connected to avoid damage and inaccurate readings.
• 2. Inspect the exhaust temperature sensor regularly for any signs of wear or damage. Look for issues like loose connections, cracks, and corrosion. Address any problems immediately to prevent further damage to the sensor.
• 3. Clean the exhaust temperature sensor regularly to avoid the buildup of dirt and grime that can affect its performance. Use a soft cloth and mild cleaning solution to wipe the sensor carefully.
• 4. Follow the manufacturer's instructions on how to maintain the exhaust temperature sensor. Adhere to the recommended maintenance schedule and use the right tools and equipment.
• 5. Protect the sensor from physical damage. Take precautions to avoid hitting or bumping the sensor, as it can lead to sensor damage.

How to Choose Exhaust Temp Sensor

Choosing the right exhaust temperature sensor isn't just about picking a device off the shelf. It requires understanding the specific needs of the application, the characteristics of the sensors, and the installation requirements. Here's a comprehensive guide on how to choose the right exhaust temperature sensor:

• Temperature Range: Consider the maximum and minimum temperatures the exhaust system will reach. Choosing a sensor with a wide temperature range ensures it can handle all temperature variations without damage or inaccurate readings.
• Placement: Where the sensor is placed in the exhaust system will affect its readings and the type of sensor that is most appropriate. For example, a sensor placed before the catalytic converter will measure the temperature of the exhaust entering the converter, while one placed after will measure the temperature of the exhaust leaving the converter.
• Response Time: A fast response time is crucial for applications where temperature changes rapidly. For instance, a sensor with a quick response time is needed in racing or high-performance vehicles. On the other hand, slower response times might be acceptable in standard or low-speed applications.
• Accuracy: Consider the required measurement accuracy for the specific application. High-precision sensors are essential in processes where exact temperature control is critical. On the contrary, lower accuracy levels can suffice in less critical applications.
• Durability: Exhaust temperature sensors face harsh conditions, including high temperatures, vibrations, and exposure to corrosive exhaust gases. Therefore, selecting durable sensors made from robust materials that can withstand these conditions is essential.
• Compatibility: Ensure the chosen sensor is compatible with the existing exhaust system and the vehicle's or equipment's electronic control unit (ECU or ICS). Consider factors such as sensor size, mounting options, and electrical connection type.
• Features: Consider additional features that may be beneficial for the specific application. For example, some exhaust temperature sensors have built-in signal conditioning, such as amplification or filtering, to improve measurement accuracy and reliability.
• Cost: Set a budget for purchasing exhaust temperature sensors. Consider the long-term benefits of choosing high-quality, reliable sensors, even if they come at a higher initial cost.
• Supplier Reputation: Choose reputable suppliers and manufacturers known for their quality and reliability. Research customer reviews and recommendations to ensure the chosen supplier meets expectations.

How to DIY and replace exhaust temp sensor

Before attempting to replace an exhaust temperature sensor, it's important to note that it requires some basic knowledge of car mechanics. Follow the steps below:

• Identify the right sensor

  Check the owner's manual or service manual to know the exact location of the sensor within the exhaust system. One may need to lift the car using a jack and place it on a level surface.

• Gather the necessary tools

  One will need a wrench set, pliers, a screwdriver set, a socket ratchet, and an O2 sensor removal tool. It's also important to have a new exhaust temperature sensor that is compatible with the vehicle make and model.

• Disconnect the battery

  To prevent any electrical short circuits or damage, disconnect the negative cable of the battery before starting the replacement process.

• Remove the old sensor

  Locate the connector cable of the exhaust temperature sensor and carefully unplug it. Use the appropriate tool to unscrew the sensor from its mounting place in the exhaust pipe. Be careful not to damage the threads or the surrounding pipe.

• Install the new sensor

  Carefully screw the new sensor into the mounting location and tighten it securely. Avoid over-tightening, as this can damage the sensor or the exhaust pipe. Once done, connect the vehicle's electrical system to the sensor and ensure the connection is secure.

• Reconnect the battery

  After completing the installation, reconnect the negative cable to the vehicle's battery.

It's important to note that different vehicles have different exhaust temperature sensor placements. Therefore, it may be necessary to consult a professional mechanic for help.

Q and A

Q1. Where is the exhaust temperature sensor located?

A1. The exhaust temperature sensor is placed on the exhaust pipe, typically before and after the catalytic converter, to monitor the temperature of the exhaust gases.

Q2. What kind of problems can a faulty exhaust temperature sensor cause?

A2. A faulty exhaust temperature sensor can lead to several issues, including increased emissions, reduced fuel efficiency, potential damage to the catalytic converter, and overall engine performance problems. The car's check engine light may also be activated, indicating a problem.

Q3. Can one drive with a faulty exhaust temperature sensor?

A3. While it may be possible to drive with a faulty exhaust temperature sensor, it is not recommended. The issues caused by the faulty sensor can lead to increased emissions and potentially damage other components of the exhaust system, such as the catalytic converter. Furthermore, it can affect engine performance and fuel efficiency.

Q4. What is the average lifespan of an exhaust temperature sensor?

A4. The exhaust temperature sensors are designed to last for a long time, often between 100,000 to 150,000 miles. However, their lifespan can be affected by several factors, including exposure to extreme conditions, contamination, and physical damage.

Q5. How is an exhaust temperature sensor checked?

A5. The sensor can be tested using a multimeter to check its resistance and compare the readings with the manufacturer's specifications. It can also be checked using an oscilloscope to examine the output signal.