Where is the outside temperature sensor located?

The location for an outside temperature sensor depends on the device, but outside temperature sensors are typically placed outdoors to measure ambient air: in cars behind the bumper or near the grille; on homes they are mounted outside; and in weather stations they sit in open, shaded areas.

In this article, we break down the common placements by device type and explain how to identify, check, and verify sensor locations. While exact spots vary by model, these guidelines cover the most frequent configurations and provide practical tips for ensuring accurate readings.

Automobiles: where the sensor sits

Car manufacturers place the outside air temperature (OAT) sensor in a location that best reflects the ambient air entering the vehicle’s climate control system. The exact spot can vary by model, but several locations are common across many vehicles.

• Behind the front bumper near the grille, often protected by the bumper reinforcement.


• In the lower grille area or near the fog-light housing.


• Inside the engine bay behind the bumper or in a fender-well area.


• Some models place it near the left or right wheel well behind trim panels.

Because placement differs by model and year, consult your vehicle’s owner’s manual or a service manual for your exact coordinates and any model-specific quirks. If the displayed temperature seems off, check for debris, obstruction, or sun exposure near the sensor location.

Home thermostats and HVAC systems: external sensor placements

Many modern HVAC systems use an external outdoor sensor to provide accurate outdoor readings to the thermostat. Placement aims to avoid direct sun, heat sources, and obstructions that could skew readings.

• Mounted on an exterior wall about 1.5–2 meters (5–6.5 feet) high, preferably on a shaded or north-facing surface.


• Outdoor sensors may be in a small weatherproof enclosure or mounted on a sheltered section of the wall, away from vents or exhausts.


• Wired sensors require running cable from the sensor to the thermostat or control board; wireless sensors rely on a stable signal between devices.


• Some systems use a remote outdoor sensor placed away from walls or heat sources, such as on a post or fence.

If readings seem inconsistent, verify the sensor isn’t blocked by shade from a nearby structure, ensure proper cable connections if wired, and refer to the installation guide for your specific model and sensor type.

Weather stations and standalone outdoor sensors: proper setup

Personal weather stations (PWS) rely on an outdoor sensor unit that should be installed in an open area to avoid microclimates created by buildings, walls, or vegetation. Proper placement is crucial for accurate data like temperature, humidity, and wind.

• Mounted on a mast or pole at about 1.5–2 meters (5–6.5 feet) above the ground.


• Placed in a radiation shield or ventilated enclosure that blocks direct sun while allowing air to circulate.


• Positioned away from buildings, roofs, exhausts, sprinklers, and heat sources to minimize heat reflection and warming of readings.


• Ensure cables (if wired) are weatherproof and neatly routed to avoid damage or interference; wireless units should maintain a clear line of sight and good signal.

Follow the manufacturer’s guidance for wind exposure, mounting height, and shield type; regular checks help maintain reading accuracy over time.

Summary

Outside temperature sensors are placed to measure true ambient air and vary by device: cars typically position sensors behind the bumper or near the grille; home outdoor sensors sit on exterior walls or in sheltered outdoor boxes; weather stations place sensors on open poles with radiation shields. If readings seem off, verify the sensor location, protect it from direct sun, and consult the device’s manual for model-specific guidance.

Why is my car reading the wrong outside temperature?

Your car is likely reading the wrong temperature due to a faulty ambient temperature sensor, heat from the road, or sensor connection issues. The most common reasons are a dirty or damaged sensor, a loose electrical connection, or radiant heat from the road surface. 
Sensor and connection issues

• Dirty or damaged sensor: Dirt, bugs, and road debris can accumulate on the sensor, causing it to give incorrect readings. The sensor itself may also be physically damaged. 
• Loose or corroded connection: The wires connecting to the sensor can become loose or corroded over time, leading to an intermittent or inaccurate signal. 

Environmental factors

• Heat from the road: The sensor is often located low on the car, near the ground. Road surfaces like asphalt absorb a lot of heat from the sun and radiate it upwards, making the sensor read a higher temperature than the actual air temperature, especially when the car is stopped in traffic. 
• Radiant heat from the car: The sensor can also be affected by radiant heat from the engine and other metal parts of the car. 

How to fix it

1. Locate the sensor: It is usually behind the front grille, in the front bumper, or near the radiator support. 
2. Inspect and clean: Check for dirt or damage on the sensor. Unplug the sensor, clean the connector with contact cleaner, and then plug it back in securely. If the sensor looks damaged, it will need to be replaced. 
3. Check the connection: Make sure the wiring harness is securely plugged in and free from corrosion. 
4. Consider a software update: Sometimes, the issue can be a software glitch in the instrument cluster. A dealership or mechanic can check for available updates. 
5. Consult a professional: If cleaning and checking the connection don't work, the sensor itself is likely faulty and needs replacement. It may also be a more complex electrical issue, so a professional mechanic can provide a more precise diagnosis. 

What are the symptoms of a bad outside temperature sensor?

Symptoms of a bad ambient air temperature sensor include a check engine light, inaccurate or erratic temperature readings on the dashboard, and poor climate control performance, such as the air conditioner not cooling or the auto mode not working. It can also lead to worse fuel economy and potential engine issues like cold start problems, rough idling, or even stalling.
 
Engine and performance

• Check engine light: The vehicle's computer detects a problem and turns on the check engine light. This may be accompanied by trouble codes like P0070 to P0074. 
• Poor fuel economy: An inaccurate sensor can cause the engine control unit (ECU) to use more fuel to compensate for a falsely cold temperature reading, leading to reduced fuel efficiency. 
• Engine start and idle problems: You may experience a rough idle, difficulty starting, or engine stalling, especially during cold starts. 
• Black smoke from exhaust: Poor combustion due to incorrect temperature data can lead to black smoke from the exhaust. 

Climate control and A/C

• Incorrect or fluctuating temperature display: The temperature shown on the instrument cluster may be wildly inaccurate, or the reading could jump around erratically. 
• Inconsistent or poor cooling: The air conditioning may not blow as cold as it should, or it may cycle on and off inconsistently. 
• A/C auto mode failure: The automatic climate control system may stop working correctly, with the compressor clutch not engaging when it should. 

Where are car outside temperature sensors located?

The outside temperature sensor is most commonly located under the front bumper, behind the grille, or in the lower part of the front fascia. Less common spots include the side mirror housing, such as on certain Ford models. Its position is designed to get an accurate reading of the outside air by being shielded from engine heat but still exposed to the open air.
 
This video shows the location of the ambient air temperature sensor on a Ford C-Max: 1mAuto Repair GuysYouTube · Mar 30, 2020
Common locations

• Behind the front bumper/grille: This is the most frequent location, often requiring removal of the bumper cover or grille to access. The sensor is typically mounted on the inside of the bumper or grille structure. 
• Under the front of the car: On some vehicles, the sensor is placed under the front of the car near the bumper and may be accessible from underneath. 
• Behind a headlight: On some models, such as certain Fords, the sensor can be found in the corner behind a headlight. 

Other potential locations

• Inside the side mirror housing: Some vehicles, particularly certain Ford models, place the sensor in the side mirror assembly. 

Why it's located there

• The goal is to place the sensor where it can measure the surrounding air temperature accurately, away from the heat generated by the engine or road surface. 
• While a location behind the front bumper is generally good, it can still show a higher temperature when the car is stopped due to heat radiating from the radiator and A/C condenser. 

You can watch this video to learn how to test the ambient air temperature sensor: 51sHVAC Mechanic YouTube · Jul 8, 2024

How do I reset an outside temperature sensor?

To reset a car's ambient temperature sensor, try the button reset procedure: press and release the A/C and recirculation buttons simultaneously, then press the A/C button again within two seconds. For some models, disconnecting the vehicle's battery for about 10 minutes can also work. If these methods fail, you may need to clean the sensor or the sensor itself could be faulty. 
Method 1: Button reset (most common for vehicles) 
This video demonstrates how to reset the ambient temperature sensor using the button method: 58sEasy StepsYouTube · Feb 5, 2023

1. Press and hold: the A/C and recirculation buttons on your HVAC panel at the same time. 
2. Release: both buttons. 
3. Within two seconds, press the A/C button again. 
4. If this doesn't work, you may need to drive the vehicle at speeds above 20 mph for at least five minutes to allow the system to recalibrate. 

Method 2: Battery disconnect 
This video shows how to disconnect the battery to reset the ambient temperature sensor: 59sNexologyYouTube · Aug 7, 2025

1. Disconnect the negative terminal: of the car's battery.
2. Wait: for at least 10 minutes to allow the system to completely reset.
3. Reconnect: the battery terminal. 

If the problem persists

• Clean the sensor: The sensor, often located in the front grille, can get dirty. Inspect and clean it carefully. 
• Check for damage: After cleaning, if the temperature reading is still inaccurate, there may be damage to the sensor or its wiring. 
• Consider a replacement: If the sensor is physically damaged or a cleaning doesn't help, it may need to be replaced.