Is your car getting too hot? Is the temperature sensor on your dashboard stuck at cold or hot? Additionally, do you have trouble starting your engine or poor car idling?
If you answered yes to any of these questions, your temperature sensor may be to blame. You should test it to see if it needs to be replaced or not. The temperature sensor in your car or truck is an important part of the cooling system for your engine, so if your car or truck is overheating, you may have a defective sensor. Luckily, changing a temperature sensor only requires putting in a new one.
To make sure the issue is with your sensor and that there isn’t a more serious problem that has to be fixed, you should test it first. You may quickly take a few readings with your handy multimeter to determine whether your sensor is working properly. In this post, I will show you how to check the temperature sensor with a multimeter.
What is a temperature sensor and what does it do?
A sensor that measures temperature is called a temperature sensor. It can be used to regulate a process or to monitor the environment when combined with other devices. For instance, a temperature sensor in an HVAC system can be used to determine when a room has reached the ideal temperature and then send an instruction to the heating or cooling system to switch off. Thermocouples, RTDs, and PT100 are the three temperature sensors most frequently utilized in industrial applications.
Symptoms Of A Bad Temperature Sensor
The signs of a faulty temperature sensor are easy to identify because of the role it plays in the engine and how it influences an ECU’s functions.
Overheated vehicles
When the engine needs cooling, the ECU may receive a constant hot signal from a faulty temperature sensor, which prevents the fan from ever turning on.
The engine continues to heat up until it overheats, which could be a fire hazard.
Poor Ignition Timing
The ECU uses information from the temperature sensor, as was already indicated, to time ignition. As a result of faulty ignition timing, the engine will be difficult to start when the temperature sensor is faulty.
Inaccurate Fuel Injection
Poor fuel injection into the engine as a result of a faulty temperature sensor creates a wide range of additional symptoms.
Black smoke coming from the exhaust pipe, low fuel economy, problematic engine idle, and generally subpar engine performance are a few examples.
Long-term maintenance under these circumstances could harm your engine.
safety precautions
- When working with temperature sensors and multimeters, make sure you always put on the proper personal protective equipment (PPE), such as gloves and safety glasses.
- To avoid electric shock, make sure the equipment is correctly grounded and insulated.
- Keep the sensor and multimeter away from anything that could catch fire or explode.
- Before attaching the multimeter probes to the sensor, turn off the power source.
How To Check Temperature Sensor With Multimeter
Locate the temperature sensor
You must open your car in order to find the temperature sensor. Near the thermostat housing is often where the majority of the temperature sensors are located. However, the temperature sensor might also be linked to a cylinder head, depending on the make and type of your car.
Additionally, you can find the thermostat housing by following the upper radiator hose, which is located on the engine side. Therefore, look for a large nut with an electrical connector over it and two electrical wires coming out of the connector. Modern automobiles typically have this design, but older versions only have one wire coming out of the connector. Additionally, in larger trucks, sensors are frequently hidden behind the intake plenum, requiring the removal of the intake to have access to them.
Take Out The Temperature Sensor
The temperature sensor is connected to the engine through a wired terminal. It has metal terminals that attach to a wire harness, so you just need to unplug these two.
Simply unhook the wire harness from the sensor.
Make sure the engine is turned off and has been idling for at least 15 minutes before opening the hood of your automobile to locate and remove the temperature sensor. This will prevent you from being burned.
Your multimeter will be useful after you have found and removed the temperature sensor from the engine.
Position Multimeter Leads
Put the leads of your multimeter on the temperature sensor’s terminals. Although some sensors have up to five terminals, make sure the probes are attached to the sensor plug on both ends. It is much simpler to complete the process when alligator clips are used. You don’t want the multimeter probes to touch when you connect them.
The black probe is simply clipped to the terminal on the far left, and the red probe is clipped to the terminal on the far right.
Dip a Sensor In Cold Water
The sensor must be submerged in both hot and cold water to obtain a reference temperature for measurements.
You obtain 180 ml of water, add ice cubes, and make sure the water is about 33 °F (1 °C) in temperature. A computerized thermostat might be beneficial.
Take Measurements
You must check the sensor’s voltage output in order to diagnose a temperature sensor. You do this by setting the multimeter’s dial to DC voltage and recording the results.
Try readjusting the probes on the terminals if the multimeter isn’t giving readings. You don’t need to conduct any additional tests if the sensor is still failing to give any readings.
About 5 volts is the multimeter’s optimal reading. Refer to your car’s manual for more information as this depends on the model of the temperature sensor. Make a note of any readings you receive.
In hot water, dip the sensor
Now, immerse your sensor in around 180 cc of boiling (212°F/100°C) water.
Take Measurements
Check for voltage readings while the multimeter is still set to measure DC voltage, then record them. A decent temperature sensor yields a multimeter result of roughly 25 volts in this boiling water test.
Of course, this varies by model, so you should consult the owner’s manual for your automobile or the instructions for your temperature sensor.
Analyze the Results
After doing these cold- and hot-water tests, you compare the measurements you obtained to the specifications for the model of your particular car. The sensor has to be replaced if the cold and hot data don’t add up.
Conclusion
In conclusion, using a multimeter to check a temperature sensor’s resistance is a practical method to assess its functionality. It allows you to quickly determine whether the sensor is within the expected resistance range. However, keep in mind that this method only checks the sensor’s electrical properties and not its overall performance in a real-world temperature measurement application. For a comprehensive evaluation of a temperature sensor’s functionality, it’s important to consider its datasheet and conduct actual temperature measurements under controlled conditions.
FAQs
Why Is My Temperature Gauge Not Moving?
It’s possible that the temperature gauge is not moving because the temperature sensor is damaged. Depending on the time the sensor became damaged, the gauge may be permanently stuck on hot or cold.
Does Temperature Gauge Have A Fuse?
The temperature sensor uses the fused wire to the instrument cluster instead of having its own fuse. The temperature sensor will not function if this fuse is burned, so it needs to be changed.