How to Bypass Ambient Air Temperature Sensors | Step by Step Guide

How to Bypass Ambient Air Temperature Sensors

The temperature sensor present in the ambient air of a car is a sensor used to control the air conditioning. It uses to switch off the air conditioning once the desired temperature reaches. The functioning of this sensor is effortless. The sensor can connect to the pins present inside the OBD port of a car. A VCC of 12V is also required to run this ambient air temperature sensor. The temperature sensor of a car works on a wide range of +50 degrees centigrade to -60 degrees Celsius. Let’s learn how to bypass ambient air temperature sensors.

How to Bypass Ambient Air Temperature Sensors 

How to Bypass Ambient Air Temperature Sensors 

There is a simple, safe, and reliable method for bypassing the internal air temperature sensor not to affect engine operation. It will produce the same response as if it were a valuable tool for monitoring your engine’s temperature. It will be completely safe because it will not allow excessive temperatures to proceed, the same way it should in the standard configuration. 

Here’s how to bypass the air temp sensor: 

  • Disconnect the sensor terminal at the sensor 
  • Attach the wire to a suitable +5 VDC source. 
  • Attach the other wire to the ground. 
  • Reconnect the sensor terminal to the sensor.

Bypass Ambient Air Temperature Sensor by Using a Hotwire

A hotwire is a thin wire that runs through a channel in a metal block. At a set point, temperature causes a small current to flow. The two classic ways to use a hotwire are a temperature controller for an electrical heating element or a sensor to detect an object passing by the channel.

In this case, we’re using the hotwire to act as a bypass for the ambient air temperature sensor. Since the hotwire affix to the point will always be at the same temperature as the outside air, always reading ambient temperature. It means if you want your temperature controller to work when your hotwire is cold, you will have to add a temperature sensor to detect when the hotwire is cold.

Bypass Ambient Temperature Sensor with Battery:

There are two methods for bypassing the ambient temperature sensor: 

Method 1: Open the Battery and find the ambient temperature sensor. Chop the black and red wines from the Battery to connect one end of the cables to the Battery, and the other of the coil to the terminal of the Battery. 

Method 2: Wrap the ambient temperature sensor with a piece of paper, plug in the Battery and use the Battery.

How to Bypass Ambient Temperature Sensor with Liquid Crystal? 

How to Bypass Ambient Air Temperature Sensors

The simple method injects an amount of liquid crystal (in the fluid state) into the temperature sensor volume. The liquid crystal temperature sensor should make a small amount of liquid crystal (about 10um thick) in a small glass capillary.

The liquid crystal volume should fill with a small amount of fluid. Since the liquid crystals are thermotropic, their alignment would change with the temperature. The liquid crystal volume should have a transparent window through which infrared rays pass.

The rest of the sensor may fill with air when the ambient temperature sensor locates in the liquid crystal. The liquid crystal changes its phase according to the ambient temperature. The phase change would alter the refractive index of the liquid crystals, which would, in turn, changes the number of infrared rays passing through the sensor.

Thus the phase change, refractive index, or infrared rays could all be ways to measure ambient temperature.

How to Bypass the Ambient Temperature Sensor with ECU?

How to Bypass the Ambient Temperature Sensor with ECU

In older versions of cars, there is no anti-theft system. You can remove the temperature sensors. And then connect the engine to the original ECU. It would help if you found the temperature sensor wiring. It will be near the thermometer. 

Now, you can see the wires with yellow insulation. First, attach these wires to the original ECU connector. Similarly, you can join the other cables. But it is essential to wire them correctly. If you get the polarity wrong, then it may damage the engine.

Bypass Ambient Air Temperature Sensor by Using a Resistor

Bypass ambient air temperature sensor in Buick Regal using a resistor. This sensor regulates the temperature and transfers this information to the car. It is so that the air conditioning and heating systems can adapt to the surrounding temperature.

We use this sensor to inform the car that our application’s outside temperature is 0 Celsius. So the vehicle will not activate the heating system even when the cooling temperature is set to 0 Celsius, giving us heat at any time of the year and the need for a windshield defrost.

Safety Tips to Bypass Ambient Air Temperature Sensor

  • Don’t modify the ambient air temperature sensor unless you know what you’re doing. 
  • If you modify the ambient air temperature sensor, do yourself a favour and make sure the ambient air temperature sensor is safe and cannot be accessed by anyone else.
  • As always, use your own best judgment in any situation. You cannot consider anyone answerable for the deterioration that may result from ambient air temperature sensor modification.
  • Connect to OBD II-ready vehicles, and check the ambient air temperature sensor.
  • Easy to use: Connect your vehicle to the app and bypass the ambient air temperature sensor.

Frequently Asked Questions

What’s your favourite way to disable your ambient temperature sensor?

  • Remove the Battery.
  • Hold down the potential button for 10 seconds. 

Does Ambient Air Temperature Sensor Affect AC?

  • Yes, they affect the thermal capacity of the unit.
  • Yes. Too warm air is terrible for the compressor.

Which Ambient Temperature Sensor Affects The Engine The Most?

  • Outside temperature sensor – this affects fuel injection timing. 
  • Engine temperature sensor – this is used for engine management. 

What Does The Ambient Air Temperature Sensor Connect?

It helps the ECU to control the engine temperature and optimize performance. It also delivers information to ECU.


We have tried our best to write about ambient air temperature sensor bypass. It can be a helpful trick to prevent potential situations like the one above if you have any other cross-question or concerns about bypassing the ambient air temperature sensor. We are always present to deliver helpful guidance on such a topic.