P0072 on 2017-2024 Chrysler Pacifica: Ambient Air Temperature Sensor Causes and Fixes

What's Unique About the 2017-2024 Chrysler PACIFICA

On the Chrysler Pacifica, the Ambient Air Temperature sensor is located in a vulnerable position behind the front grille, making it and its wiring susceptible to damage from road debris, water, and corrosion. Chrysler has issued Technical Service Bulletins (TSBs) for this and related codes (P0071, P0073) across various models. One internal FCA communication (STAR Case #9004547) specifically notes that after experiencing this code, a specific diagnostic procedure must be followed, and in some cases, technicians are instructed to call FCA before replacing the sensor, suggesting a known issue with either the part, the diagnostic process, or a required software update. A specific TSB for 2022 models also identifies a poorly sealed ground point (G917A) as a source of water intrusion that can cause this code.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on.
• Incorrect outside temperature reading on the dashboard or infotainment screen (often stuck at -40°F or a similar impossible value).
• Automatic climate control system does not work properly (e.g., A/C won't blow cold, or heat is on unexpectedly).
• Seat heaters may turn on automatically due to the false cold reading.
• Auto Start/Stop system may be disabled.
• Cooling fans may run continuously as a fail-safe measure.

Most Likely Causes

1. Failed Ambient Air Temperature (AAT) Sensor 🔴 High Probability The sensor is exposed to the elements (water, salt, road debris) in its location behind the front grille, which can lead to internal short circuits and premature failure.
   How to confirm: After checking wiring, test the sensor's resistance with a multimeter. The resistance should change with temperature. If it's shorted (near zero resistance), it has failed. A reading of -40°F on the dash is a very common symptom of a failed sensor.
   Typical fix: Replace the Ambient Air Temperature sensor. This is a simple plug-and-play part.
   Est. part cost: $25-$50
2. Damaged Wiring or Connector 🟡 Medium Probability The wiring harness leading to the sensor is in the front fascia, where it can be damaged by minor impacts, road debris, or water intrusion leading to corrosion on the connector pins. Some owners on forums note that poor grounding points in the engine bay can also cause various electrical faults on this platform.
   How to confirm: Visually inspect the wiring and connector for breaks, chafing, or green/white corrosion on the pins. Perform a continuity test on the wires from the sensor connector to the next harness connection point. Check the signal wire for a short to ground.
   Typical fix: Repair the broken or shorted wire(s) or replace the connector pigtail. Ensure the connection is sealed against moisture using dielectric grease or heat-shrink tubing.
   Est. part cost: $15-$40

Rare But Worth Checking

• Faulty Powertrain Control Module (PCM): This is very rare. The sensor and wiring should be thoroughly tested and ruled out before considering the PCM as the cause. A faulty PCM typically causes multiple other codes and more severe drivability issues.
• Corroded Ground Splice (G917A): On 2022 models, a specific ground splice is known to allow water intrusion, causing AAT sensor circuit faults. This is documented in TSB 08-175-22 and requires resealing the ground point, which is located under the battery tray on non-hybrid models.
🎬 See this guide to find all Chrysler Pacifica ground locations

Diagnosis Steps

1. Read the trouble code with an OBD-II scanner to confirm P0072 is active or stored.
2. Observe the outside temperature display on the dashboard. If it reads an illogical value like -40°F, it strongly suggests an AAT circuit fault.
3. Locate the AAT sensor. On the Pacifica, it is typically clipped into a bracket behind the lower front grille.
4. Visually inspect the sensor and its electrical connector for any signs of physical damage, corrosion (green crust), or loose pins.
5. Disconnect the sensor. Inspect the connector terminals for moisture or corrosion. Clean with electrical contact cleaner if necessary.
6. With the key on and engine off, use a multimeter to check for a reference voltage (usually around 5 volts) on one pin and ground on the other. A 'Circuit Low' code often indicates a short to ground on the signal wire (often labeled G31), which would result in a reading near 0 volts.
7. If the wiring and voltage appear correct, test the sensor itself. Measure the resistance across the sensor's pins. A healthy sensor's resistance changes with temperature (a thermistor). A reading near zero ohms indicates a shorted sensor that needs replacement.
8. If the sensor tests good, perform a continuity test on the wiring harness to check for shorts between wires or shorts to ground.
9. If the vehicle is a 2022 model, inspect ground G917A for corrosion per TSB 08-175-22.
10. After the repair, clear the trouble code with the scanner and drive the vehicle to ensure the code does not return and the climate control functions correctly.

Parts You'll Likely Need

• Ambient Air Temperature Sensor (OEM #5149264AB (supersedes 5149264AA, 5293138AA)) — This sensor is the most common failure point for code P0072 due to its exposed location and electronic nature.
  Trusted brands: Mopar, Dorman, Delphi, Standard Motor Products
  OEM price range: $28-$45
  Aftermarket price range: $15-$35
• Ambient Air Temperature Sensor Connector Pigtail — If the original connector is corroded or damaged, replacing the pigtail is the proper repair. The exposed location makes connector damage common.
  Trusted brands: Mopar, Dorman, Standard Motor Products (e.g., S-1918)
  OEM price range: $20-$40
  Aftermarket price range: $10-$25

Related Codes That Often Appear With This One

• P0071 — This code for 'Ambient Air Temperature Sensor Range/Performance' can be triggered by similar intermittent wiring issues or a failing sensor.
• P0073 — This code for 'Ambient Air Temperature Sensor Circuit High' indicates an open circuit, which can be caused by the same wiring harness that might cause a short (P0072). Water intrusion can cause both shorts and opens intermittently.
• U11E9 — TSB 08-175-22 links ambient temperature sensor faults to this code, which indicates a loss of communication with the Active Grille Shutter (AGS). The AAT sensor and AGS are located near each other and may share a wiring harness or common ground (G917A), making them both vulnerable to the same damage.

Technical Service Bulletins (TSBs) & Recalls

• 9004547: An internal FCA communication that mentions P0072 and directs technicians to call FCA before replacing the ambient air temp sensor on Pentastar Upgrade Engines, suggesting a complex issue.
• 18-044-26 (Dated 2017-03-21): Defines P0072-00 as Ambient Air Temperature Sensor Circuit 'A' Low, confirming the manufacturer's definition.
• 08-175-22 (Dated 2022-09-17): Identifies water intrusion at ground G917A as a cause for P0072 and other AAT codes on 2022 Pacificas built before mid-April 2022.

Platform-Specific Known Issues

• FCA Internal Directive on Sensor Replacement: An internal communication (STAR Case #9004547) for the Pentastar Upgrade Engine instructs technicians to follow a specific diagnostic procedure for P0072 and to contact an FCA hotline before replacing the sensor. This indicates a known pattern of failure where a simple part swap may not be the complete fix, possibly requiring an updated part or software calibration.
• Real-World Repair Story: Front-End Damage: A common story on forums involves this code appearing after a minor front-end impact or after hitting road debris. One user on a Chrysler forum reported a P0070 code and a -37°F reading after a history of front-end damage, which was ultimately traced to the wiring harness rather than the sensor itself.

Mechanic-Grade Diagnostic Values

• AAT Sensor Signal Voltage (Live Data) — expected: Typically 0.5V to 4.5V. A real-world example showed 2.33V at 62°F (16.7°C).. Failure: A voltage reading below 0.5V confirms the 'Circuit Low' condition.
• AAT Sensor Connector Voltage (Unplugged) — expected: Approximately 5.0V on the reference wire.. Failure: 0V may indicate a problem with the PCM or the reference wire. If the signal wire shows 0V when plugged in, it points to a short to ground.
• AAT Sensor Resistance — expected: Resistance changes with temperature (thermistor). For example, a common automotive thermistor might be ~10,000 ohms at 77°F (25°C) and decrease as temperature rises.. Failure: Near zero ohms indicates a shorted sensor. An open circuit (infinite resistance) would typically set a P0073.

Scan Tool Commands That Help

• wiTECH (or equivalent professional scanner): View Live Data (AAT Sensor Voltage/Temp) — This is the first step to see what the PCM is reporting from the sensor, which may differ from what the dashboard displays, indicating a communication issue.
• wiTECH: Flash Reprogram Instrument Cluster / PCM — Used in edge cases where an inaccurate temperature display is caused by a software glitch, or if a TSB requires a calibration update to resolve the fault.
• Professional Scanner: Sensor Simulation — To test the PCM's input circuit. The tool commands the PCM to simulate a sensor reading to verify the module is processing the signal correctly, helping to isolate a faulty PCM.

Wiring & Ground Locations

• G917A — Under the battery and battery tray on non-PHEV models.. TSB 08-175-22 identifies this headlamp and dash ground splice as a point of water intrusion and corrosion on 2022 models, which can directly cause AAT sensor circuit faults like P0072.
• AAT Sensor Connector — Behind the lower front grille/bumper area, clipped to a bracket.. This is the primary connection point for the sensor. It is exposed to road debris and moisture, making it a common point of failure due to corrosion or physical damage.
• G31 (Circuit) — This is the circuit identifier for the AAT sensor signal wire running from the sensor to the control module.. When diagnosing, testing this specific wire for a short to ground is the key to confirming the cause of a P0072 code.

Real Owner Repair Stories

• Reddit user anvilpounder47 in r/ChryslerPacifica (Chrysler Pacifica (year not specified)) — Ambient temp sensor reading -30°F when it was 47°F outside. Auto Start/Stop system became unavailable.
  ❌ Tried (didn't work) Initially unsure if the battery was the cause for the start/stop issue, but batteries had been recently replaced.
  ✅ What actually fixed it The user researched and found that an erroneous reading from the AAT sensor will disable the start/stop system as a protective measure. Replacing the faulty AAT sensor was the implied fix for both issues.
• Chrysler Forum user 'jgbat' (2005 Chrysler Pacifica) — Randomly throwing P0072, Check Engine Light on, A/C not working, and HVAC display stuck at -40°F.
  ❌ Tried (didn't work) Replacing the AAT sensor did not change the symptoms., Splicing in a new harness pigtail.
  ✅ What actually fixed it The repair was inconclusive but revealed a critical diagnostic clue: After replacing the harness, the user's OBD-II scanner showed the PCM was reading the correct ambient temperature (62°F with 2.33v), but the HVAC display on the dash remained at -40°F. This indicates the fault was not with the sensor or its circuit to the PCM, but likely a communication failure between the PCM and the Body Control Module (BCM) or HVAC control module.

OEM Part Supersession History

• 5293138AA, 5149264AA → 5149264AB — Standard part evolution. The reason for the update is not officially documented but is typically for improved durability, material composition, or a change in supplier.

Model Year Variations Within This Range

• 2022 (built on or before April 25, 2022): These models are subject to TSB 08-175-22, which identifies a potential for water intrusion at ground splice G917A, leading to AAT sensor codes like P0072. The fix involves resealing the ground point.