P0073 on a Nissan Sentra means the ECM has detected that the ambient air temperature (AAT) sensor’s circuit voltage is above the expected operating range: which almost always means the sensor itself has failed open (producing no signal or a false high-voltage signal), the wiring to the sensor has been damaged, or in rare cases the connector has a poor ground connection causing the signal voltage to float high.
Unlike many engine codes, P0073 rarely causes drivability problems because the ambient air temperature sensor primarily informs the climate control system and a few fuel strategy calculations, but it will illuminate the check engine light and may display an incorrect outside temperature reading on the instrument cluster.
“Got P0073 on my 2019 Sentra and panicked thinking it was something serious. Turned out the ambient air temp sensor had corroded at the connector: it’s right in the front bumper area and gets hit with road salt and water constantly. Cleaned the connector with electrical contact cleaner and the code hasn’t returned in 8 months. Cheapest fix I’ve ever had on a car.”: Omar Hassan, 2019 Nissan Sentra SV owner
Understanding P0073 on the Nissan Sentra
What the Ambient Air Temperature Sensor Does
The ambient air temperature sensor is a thermistor: a resistor that changes resistance based on temperature. The ECM supplies a 5V reference voltage through a resistor, and the sensor completes the circuit to ground. As temperature increases, the sensor resistance decreases, which lowers the signal voltage. At cold temperatures, resistance is high and voltage is higher. When the circuit is open (broken wire, disconnected connector, or failed sensor), the ECM sees the full 5V reference without any pull-down from the sensor: a voltage reading above the maximum calibrated value for any real-world temperature. P0073 (circuit high) stores when this condition persists.
Where the Ambient Air Temperature Sensor Is Located on the Nissan Sentra
On most Sentra generations, the AAT sensor is located in or near the front bumper, often integrated into the condenser area or mounted behind the lower grille. This location exposes it to the worst road environment: water spray, road salt, and debris.
Why P0073 Causes Instrument Cluster Display Issues
The ECM uses the AAT sensor data to display the outside temperature on vehicles equipped with that feature. With P0073 active, the displayed temperature may read extremely high (the default for an open circuit), show “—,” or display an erratic value.
Causes of P0073 on Nissan Sentra
Cause 1: Corroded or Damaged Sensor Connector (Most Common)
Given the sensor’s location in the front bumper area, connector corrosion is the most frequent cause of P0073 on the Sentra. Road salt, moisture, and debris cause the connector terminals to oxidize, increasing contact resistance until the circuit appears open to the ECM. How to inspect and repair the connector:
- Locate the AAT sensor (typically front bumper area, check a Sentra-specific diagram for your generation)
- Disconnect the connector and inspect the terminals for green/white corrosion or physical damage
- Clean with electrical contact cleaner and a small brush or terminal cleaning tool
- Apply dielectric grease to the clean terminals before reconnecting to prevent recurrence
- Clear the code and monitor for recurrence This fix costs $5 to $15 in supplies and resolves the code in many cases.
Cause 2: Failed Ambient Air Temperature Sensor
If the connector is clean and the code persists, the sensor itself has failed internally. Testing is straightforward: Resistance test: disconnect the sensor and measure resistance across its two terminals. Compare to the Nissan specification for the current ambient temperature. The 2013 to 2019 Sentra AAT sensor typically shows:
- 0°C (32°F): approximately 5,800 to 6,800 ohms
- 20°C (68°F): approximately 2,000 to 2,500 ohms
- 40°C (104°F): approximately 800 to 1,000 ohms Infinite resistance (OL) confirms a failed open sensor. Ambient air temperature sensor replacement cost on Nissan Sentra: $15 to $50 for the sensor. Labor: 20 to 45 minutes (some locations require bumper fascia partial removal). Total at a shop: $60 to $150.
Cause 3: Damaged Wiring Between Sensor and ECM
A broken wire due to impact damage, rodent activity, or abrasion can cause P0073 without sensor failure. Trace the wiring from the sensor connector back toward the ECM, looking for obvious damage. A continuity test confirms wire integrity.
Frequently Asked Questions
What Does P0073 Mean on a Nissan Sentra?
P0073 means the ambient air temperature sensor’s signal circuit voltage is above the calibrated operating range. This indicates an open circuit caused by a failed sensor, corroded connector, or damaged wiring. The sensor typically used for outside temperature display and minor fuel strategy calculations.
Is P0073 Serious on a Nissan Sentra?
P0073 rarely affects drivability or engine performance. It will illuminate the check engine light and may display incorrect outside temperature. The code should be repaired within a reasonable timeframe to maintain accurate climate control operation and pass emissions inspections, but it is not an emergency.
How Much Does It Cost to Fix P0073?
Cleaning a corroded connector costs $5 to $15 in supplies. Replacing the sensor costs $60 to $150 at an independent shop. Wiring repair if a broken wire is found: $50 to $150. This is one of the least expensive check engine light repairs on the Sentra.