How To Fix An Unplugged Intake Air Temperature Sensor

The Intake Air Temperature (IAT) Sensor plays a crucial role in ensuring the proper functioning of an engine. Its primary responsibility is to measure the temperature of incoming air and transmit this data to the Electronic Control Unit (ECU) for analysis. 

The ECU, in turn, uses this information to adjust the air-fuel ratio, ignition timing, and other critical engine settings, resulting in enhanced fuel efficiency and reduced emissions. Given the IAT’s importance, automotive enthusiasts and repair professionals alike may be curious about the potential ramifications of unplugging this component. 

We’ll discuss the possible effects of when the intake air temperature sensor unplugged in this article and discuss its function.

Table of Contents

What Happens When An IAT Sensor Goes Bad?

The failure of the intake air temperature sensor can be due to various causes, like poor auto maintenance and repairs. If the intake air temperature sensor is unplugged it can experience problems like the check-engine light being on, the engine being hard to start, and it idling and running rough. Still, these can be avoided with regular checks.

It’s critical to work with a mechanic that focuses on the sort of vehicle you drive as they can best ensure that your car has the attention and care it needs and that key services affecting the IAT sensor are not missed.

What Happens If You Unplug The Air Temp Sensor?

Simply put, it is not suggested to drive a car without an IAT sensor. Your car could not be able to run as planned if a sensor stops functioning or develops a problem. The sensors are needed for precise fuel injection and air/fuel ratio monitoring. Engine stalling, harsh idling, stalling, and irregular power surges are often seen in combination with IAT sensor failure.

 The scary thing about such symptoms is that they’ll only become worse over time. In order to let the car “limp home” or to a dealer for maintenance, any disconnected sensor will lead the ECU to create an error code, turn on the “Service Engine” light, and enter “limp home mode.” In this mode, the engine’s features, like loss of power and slower operating speeds, worsen.

Never take out a sensor unless you plan to switch it to a different one. Additionally, keep clear from trying to fool the sensor using a fixed-value resistor since doing so can ruin the efficiency of the gas engine and ECU. It’s easy to lose the warranty and lose access to subsequent maintenance if you send the device in for maintenance.

Intake Air Temperature Sensor Symptoms

It’s crucial to be aware of the danger signs of an IAT sensor failure since the longer the issue is left unattended, the more serious the resulting damage will be. Below are the most typical signs of an IAT sensor failure:

  • Harsh Running And Rough Idling – The failure of the IAT sensor is usually followed by the following issues: engine stalls, poor idling, stumbling, and irregular bursts of power. These signs should be taken seriously since they will only get worse with time.
  • Starting The Engine Becomes Tough – It is quite difficult for daily life when your car’s engine has trouble starting. If you’re having difficulty starting your car, get it jump-started or have it taken to the nearby, most reputable auto repair facility.
  • The Check Engine Light Is On – It’s vital to get your car looked up straight away whenever the check engine light turns on. There’s a potential it has to do with the IAT sensor, but there is also a risk it may be something much more severe.

Intake Air Temperature Sensor Test

It only takes a few minutes to run an intake air temperature sensor test. This test is critical because it helps make sure that the engine of your car is working at the proper temperature. Two wires, hot and ground, link the intake air temperature sensor to the computer’s ECU.

In order to put the car’s intake air temperature (IAT) sensor, it is important to realize that the thermistor it uses can either have a 1 negative temperature coefficient or a 2 positive temperature coefficient.

When the temperature increases, the resistance of a positive temperature coefficient (PTC) thermistor rises, whereas it drops for a negative temperature coefficient (NTC) thermistor.

The intake air temperature sensor is intended to have an NTC thermistor in the subsequent testing method. To test the IAT sensor, you should first be aware of its location in the car’s engine.

How To Test IAT Sensor With Multimeter

Using A Multimeter, Check The IAT Sensor’s Resistance

  • Unplug the electrical connector from the Intake Air Temperature sensor.
  • Put the digital multimeter to an Ohms scale reading of 50K.
  • When the car’s engine stops, check the signal between the several Intake Air Temperature sensor inputs.
  • The number must be 37K ohms at 20 °C.
  • The number must be 24K ohms at 30 °C.
  • Plug the electrical connector of the Intake Air Temperature sensor.
  • For about 20 minutes, let the engine idle.
  • Stop the engine when the temperature increases.
  • Unplug the electrical connector from the Intake Air Temperature sensor.
  • Test the Intake Air Temperature sensor’s terminal resistance once more.
  • The resistance at 90 C must be 2.8K ohms.
  • The resistance at 100 C must be 2K ohms.
  • Your digital multimeter’s results must equal those above if your intake air temperature is operating correctly.

Using A Multimeter, Check The IAT Sensor’s Power Circuit

  • Stop the car’s engine and let it rest.
  • A digital multimeter should be tuned to a voltmeter.
  • Unplug the electrical connector from the Intake Air Temperature sensor.
  • Connect the black wire of the digital multimeter to the ground of the engine or battery negative terminal and the red wire to the Intake Air Temperature Sensor’s 5-volt reference wire.
  • Switch on the car without starting the engine.
  • If the intake air temperature sensor wiring is proper, the digital multimeter will read around 4.5 and 5 V.

Using A Multimeter, Check The IAT Sensor’s Ground Circuit

  • Switch off the vehicle.
  • Connect the digital multimeter’s black lead to the ground wire of the intake air temperature sensor and its red wire to the battery voltage.
  • Without starting the car’s engine, turn on the ignition.
  • If the intake air temperature sensor wire is linked to the ECU, the meter will show around 12 V.
  • Switch off the car’s ignition switch.

How Do You Reset An Air Intake Temperature Sensor?

These days, automatic temperature control and temperature displays are typical in cars. The gauge shows the temperature within the vehicle with the external temperature.

How Do You Reset An Air Intake Temperature Sensor

The ambient temperature sensor then enters the scene. The sensor analyzes the data on the outside temperature before showing it on the driver’s display.

 The ambient air temperature sensor handles AC systems’ automation. The driver display is given an accurate result of the outside temperature. If the sensor fails, it must be replaced immediately. The damaged switch must be replaced or repaired to maintain the temperature within the car. Let’s now discuss how to reset the air temperature sensor.

  • Locate the sensor. Check that you know its precise location before replacing or resetting the ambient air temperature sensor.
  • Remove the battery. Before operating on electrical appliances, the power supplies should be removed.
  • Take the sensor out. Avoid putting excessive force on the wires; disconnect the sensor.
  • Reset or swap out the sensor. The ambient air temperature sensor can be replaced or reset after removal. If the sensor is broken, you must replace it.

Conclusion

Your car could experience various issues if the intake air temperature sensor is unplugged. The engine can stall, operate poorly under acceleration, and have irregular power spikes. The engine could also idle erratically, and the check engine light could illuminate.

Never disconnect an IAT sensor except if a replacement is being installed. Anyone with the proper skills and equipment can easily check an IAT sensor using a multimeter. You can easily determine whether your IAT sensor is functioning efficiently by following the instructions provided in this article.

FAQ

Intake air temperature sensor voltage

The voltage between terminal A (GN) of the IAT sensor connector and terminal 7 of the ECU module connector should be approximately 5 volts.

Where is the intake air temperature sensor located?

This could be in the intake air tube between the air filter box and the throttle body. Directly installed MAP sensors on the inlet manifold may or may not include the IAT sensor.

How important is an intake-air temperature sensor?

While being a basic part, the intake-air temperature sensor is vital. Its job is to provide the engine management unit with a vital measurement for altering mix formulation and ignition.

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