Fix P0072: Mechanic’s solutions that WORKED

The OBD2 code P0072 is associated with the “Ambient Air Temperature Sensor Circuit Low,” indicating an issue with the circuit that measures the outside air temperature surrounding the vehicle.

This temperature data is crucial for several vehicle systems, including the management of the engine’s air-fuel mixture, the operation of the HVAC system, and in some cases, influencing the operation of the transmission and fuel economy. Let’s explore this diagnostic trouble code through the lens of the provided service cases from Dodge, Chrysler, and Toyota vehicles.

P0072 quick overview

Meaning	P0072: Ambient Air Temperature Sensor Circuit Low
Is it serious?	It’s moderately serious. While it may not immediately affect vehicle drivability, it can lead to improper engine performance and affect fuel efficiency over time.
Possible causes	– Faulty ambient air temperature sensor – Wiring or connector issues (such as corrosion, damage, or disconnection) – Problems in the vehicle’s computer system that may require a software update
How to diagnose?	Inspect the ambient air temperature sensor and its connector for damage or disconnection. Test the sensor’s resistance and compare it with manufacturer specifications. Check the wiring harness for signs of damage, corrosion, or improper connections. Consider a computer system flash or update if a relevant bulletin exists.

How to fix P0072 – learn from mechanics

I looked into P0072 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Dodge

Vehicle Information 2014 Dodge Journey SE 2.4L

Issue + Repair History

• Code P0072 persists even after clearing.
• Confusion arises as there are both air intake temperature and ambient temperature sensors.
• Air intake temperature sensor shows 118 degrees, while ambient temperature sensor shows 68 degrees.
• Different color codes indicate they are different sensors.
• Unplugged socket with violet color codes found near the coolant reservoir, but unable to locate the air ambient sensor.

Other OBD2 Codes + Test Results

• P0072 – Air ambient temperature sensor circuit

Mechanic Suggestions

• Check if the vehicle was recently in a body shop; a sensor may have been left off during repair. Sensor should be mounted behind the lower grill.
• The sensor is typically mounted behind the front bumper, at the center.

Final Fix Bulletin found regarding computer flash to address the problem. Advised the customer to bring the vehicle to the Dodge dealer for flashing the computer.

Case #2: Chrysler

Vehicle Information 2005 Chrysler Pacifica Touring 3.5L

Issue + Repair History

• Initially running with a check engine light on, code P0072.
• While checking resistance on the signal return wire with the ignition off, attempted to restart the engine resulting in no crank and no scanner communication.
• Immobilizer light flashing on the dash after the attempted restart.

Other OBD2 Codes + Test Results

• P0072 – Not specified if resolved

Mechanic Suggestions

• Check for a broken ground wire at the rear of the transmission, as similar issues have been encountered in the past.
• Perform a hard reboot by disconnecting the battery and holding the terminals together for 10 minutes.
• Scan other modules to see if communication bus is active and check for codes in the anti-theft module, which may indicate a problem with the key.
• Do a visual check for wiring problems near where testing was conducted.

Final Fix Performed a hard reboot of the computer by disconnecting the battery. The car started and the problem hasn’t returned.

Case #3: Toyota

Vehicle Information 2010 Toyota Camry LE 2.5L

Issue + Repair History

• Vehicle brought in with a check engine light on.
• Code P0072 detected, indicating an issue with the ambient air temperature sensor circuit.
• No previous repair history related to this issue.

Other OBD2 Codes + Test Results

• P0072 – Ambient air temperature sensor circuit issue detected.

Mechanic Suggestions

• Inspect the ambient air temperature sensor wiring harness for any signs of damage or corrosion.
• Test the resistance on the signal return wire of the ambient air temperature sensor to check for any abnormalities.
• Check the location of the ambient air temperature sensor to ensure it is properly installed and connected.

Final Fix

• After thorough inspection, found a loose connection at the ambient air temperature sensor connector. Reconnected the connector securely, cleared the code, and verified that the issue was resolved.

Diagnostic Step	Brief Explanation
Inspect the sensor and connector	Ensure the sensor is properly mounted and connected, especially after repairs or bodywork.
Test sensor resistance	Compare resistance values with specifications to check sensor functionality.
Check wiring and connectors	Look for damage, corrosion, or loose connections that could impair signal transmission.
Perform a computer system flash/update	Update the vehicle’s software based on manufacturer bulletins to address known issues.
Hard reboot the computer (if applicable)	Resetting the vehicle’s electrical system can sometimes resolve communication or sensor issues.

These cases demonstrate that troubleshooting the P0072 code can range from simple connector checks to more complex electrical system updates. Vehicle owners experiencing this code should start with a visual inspection of the ambient air temperature sensor and its surroundings, especially if the vehicle has recently undergone bodywork or repairs in the front bumper area where sensors are commonly located.

For persistent or unclear issues, consulting with a professional technician or dealer for a software update or deeper diagnostic work is recommended to ensure accurate and safe vehicle operation.