P0073 Code: Ambient Air Temperature Sensor Circuit High

The ambient air temperature (AAT) sensor measures the temperature of the outside air. One or more of your car’s computers use this information for functions, such as ambient temperature display on your dashboard and automatic climate control operation.

If you encounter the P0073 code, a potential problem has been detected with the AAT sensor or its circuit. Will the P0073 affect your vehicle’s drivability? Find out more about the error code P0073 with this brief guide.

What Does the P0073 Code Mean?

Diagnostic trouble code (DTC) P0073 stands for “Ambient Air Temperature Sensor Circuit High.” It indicates that there might be a problem with your vehicle’s ambient air temperature (AAT) sensor or the sensor’s circuit.

Automatic climate control systems have made it easier for users to select the right temperature for their vehicle’s cabin. One only needs to select their desired temperature and the system will do the rest. Usually, the computer that controls the climate control system is the Climate Control Module (CCM). It handles the vehicle’s heating and air conditioning components, the blend and vent door positions, the fan speed, and other related elements.

To function properly, the CCM relies on various sensors that keep track of various factors that affect cabin climate. These sensors measure factors such as engine coolant temperature, A/C clutch operation, and outside ambient air temperature.

The AAT sensor measures the air temperature outside the vehicle. It converts the temperature information into an electrical signal and sends it to the powertrain control module (PCM). Usually, the PCM shares that data with other modules (including the CCM). Together, the devices use the information to control functions, such as automatic climate control operation and the ambient temperature display on the dashboard.

The engine code P0073 registers in your vehicle’s memory if the PCM determines that the signal from the AAT is higher than its normal range.

For more information that could help you come up with a proper DIY fix for P0073, you may read our in-depth discussion about the AAT sensor and how it could trigger a trouble code.

Continue reading to learn the most likely causes of P0073.

Note: Troubleshooting and repair steps may vary depending on the vehicle make and model, the type of AAT sensors installed, etc.

What are the Possible Causes of the P0073 Code?

The P0073 code, like most OBD-II codes, has several possible causes. Listed below are just some reasons that can trigger the code. Note that determining the exact root cause for this trouble code is important for proper diagnosis and repair.

• Faulty AAT sensor
• AAT sensor circuit problems, such as damaged wiring or poor connections
• Control module issues

What are the Common Symptoms of the P0073 Code?

There are a handful of noticeable indications that the P0073 code has gotten stored in your vehicle’s memory. If you notice any or a combination of the symptoms below, you must plug in a scanning tool to verify the issue.

• Activated engine light or malfunction indicator light
• Faulty climate control functions
• Instrument cluster may not read outside temp accurately
• Overhead console may not read outside temp accurately

How to Diagnose the P0073 Code

Diagnosing OBD-II codes like P0073 is challenging because you have to narrow down the issue to a specific root cause. Given the list of possible causes, it can take quite a while for the average DIYer to get to the bottom of the P0073.

Fortunately, troubleshooting does not have to be a daunting task, especially now that there are a lot of repair guides, subscriptions, and even online tutorials available. If you’re looking to learn more about the engine code P0073, you’ll find the video resource below quite useful:

How to Fix the P0073 Code

There is no single solution for OBD-II codes because vehicles are built differently depending on the manufacturer. Special features and additional components also have varying configurations. Hence, it’s important to follow the repair instructions specifically made for your vehicle.

If you’re a seasoned DIYer, you can avail of a repair guide subscription to help you fix the P0073 code. These repair guides have detailed instructions and diagrams, plus other helpful suggestions. However, if you’re not that confident in your repair skills, you can have your mechanic do the job for you.

Other Notes About P0073

The P0073 has a moderate repair importance level. This means that this error code will not affect your vehicle’s drivability. However, it can give you and your passengers an uncomfortable driving experience as it greatly affects the climate control system.

An In-Depth Look at the AAT Sensor

The AAT sensor is a two-wire sensor with a negative temperature coefficient resistor positioned so that it reads the outside air temperature.

One of the two AAT wires receives about 4.6 volts from the ECM/PCM, Instrument Cluster, Body Computer, etc. and the other wire is a reference ground, also from the module the sensor reports to.

The reason it’s slightly less than the 5 volts delivered to three wire sensors is that there is a resistor inside the ECM/PCM on each two-wire sensor feed.

Because the sensing resistor is negative temperature coefficient, the resistance of the sensor is reduced as it gets warmer. As the resistance goes down, so does the voltage measured at the module receiving outside air temp information from the sensor. Lower voltage means hotter ambient air. Higher voltage means colder air.

If the sensor is disconnected or if a wire is chewed or cut leading to the sensor, the voltage registered by the module tops out at 4.6 volts, which is equal to -40 degrees (-40 Fahrenheit is exactly the same as -40 Celsius).

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Pro Tip: The ambient air sensor is typically mounted in front of the radiator and has been on vehicles for many years. But even on newer vehicles, this sensor very rarely reports ambient air temperature directly to the ECM/PCM, so you’ll probably never see code p0073.

The Ambient Temp sensor will typically throw a B (body) code rather than a P code. For just one example, on a 2006 Ford Explorer, the instrument cluster reads ambient air temperature from the AAT sensor and will set a B1255 code for an open Ambient Air Temp Sensor.

If you do see code p0073, you’ve probably got severed wiring, the sensor is unplugged, or the sensor is internally open.

Fixing DTC P0073 By Replacing The AAT Sensor

As mentioned previously, a faulty AAT sensor might be the culprit for a vehicle logging DTC P0073. If a faulty sensor is indeed responsible, you’ll need to get a replacement as soon as possible to fix your vehicle. Thankfully, it shouldn’t be too difficult to find a new sensor that’s built to last with CarParts.com.

The best part? You can save a lot of time and effort by using our website to get your hands on a new sensor. You can use our website’s vehicle selector. Just be sure to input the necessary details like the year, make, model, and engine of your vehicle.

Our sensors come from some of the most trusted manufacturers in the industry, each carefully selected by a team of professionals to guarantee quality and durability. In addition, you won’t have to wait too long to receive your order. Our warehouses are strategically located all over the US, meaning you can expect fast delivery.

Shop and get your new AAT sensor from CarParts.com.