An open circuit in the ambient air temperature sensor wiring, commonly a broken wire at the sensor connector or in the harness near the front bumper.; A failed ambient air temperature sensor that has drifted out of range or internally opened.; Corroded or loose terminals at the sensor connector or at the powertrain control module connector.; A short to voltage on the signal circuit, which can pull the reading high.; A faulty powertrain control module, though this is rare and should only be suspected after all circuit tests pass.; Damage to the sensor or its wiring from road debris, front-end impact, or rodent chewing.

DTC codes / P00xx · Fuel and air metering and auxiliary emission controls / P0073

P0073Ambient Air Temperature Sensor Circuit High

Q: What does code P0073 mean?

Ambient Air Temperature Sensor Circuit High. P0073 means the ambient air temperature sensor circuit is reporting a voltage higher than the powertrain control module expects, which usually indicates an open circuit or a sensor reading that is out of range. The computer has detected a signal voltage above its calibrated threshold for the ambient temperature input, so it flags the circuit as high.

P0073 means the ambient air temperature sensor circuit is reporting a voltage higher than the powertrain control module expects, which usually indicates an open circuit or a sensor reading that is out of range. The computer has detected a signal voltage above its calibrated threshold for the ambient temperature input, so it flags the circuit as high.

SystemPowertrain

Code typeGeneric (all makes)

SeverityLow

Fix difficultyIntermediate

AreaFuel and air metering and auxiliary emission controls

Symptoms you may notice

The check engine light is illuminated, often with no other noticeable symptoms.
The outside temperature display on the dashboard reads blank, dashes, or an implausible value.
Automatic climate control may behave erratically, such as blowing full hot or full cold regardless of the setting.
Remote start or battery management features may be disabled on vehicles that rely on ambient temperature data.
A scan tool may show a fixed ambient temperature value that does not change as the vehicle warms up or sits overnight.

Common causes, most likely first

An open circuit in the ambient air temperature sensor wiring, commonly a broken wire at the sensor connector or in the harness near the front bumper.
A failed ambient air temperature sensor that has drifted out of range or internally opened.
Corroded or loose terminals at the sensor connector or at the powertrain control module connector.
A short to voltage on the signal circuit, which can pull the reading high.
A faulty powertrain control module, though this is rare and should only be suspected after all circuit tests pass.
Damage to the sensor or its wiring from road debris, front-end impact, or rodent chewing.

How to diagnose and fix it

Connect a scan tool and read the ambient air temperature sensor value in live data, comparing it to a known-good thermometer reading after an overnight cold soak.
Visually inspect the sensor and its connector at the front of the vehicle for physical damage, corrosion, or pushed-out pins.
Disconnect the sensor and measure resistance across its terminals, then compare to the manufacturer's temperature-resistance chart for the current ambient temperature.
Check the signal circuit for an open by measuring continuity from the sensor connector to the powertrain control module, and check for a short to voltage with the key on.
Check the sensor ground circuit for excessive resistance or an open, repairing any damaged wire or terminal as needed.
If the circuit tests good and the sensor resistance is out of specification, replace the ambient air temperature sensor and clear the code.
After repairs, clear the diagnostic trouble codes and verify the ambient temperature reading updates correctly during a road test and that the code does not return.

Why ambient sensor codes get misdiagnosed

A common mistake is replacing the ambient air temperature sensor when the real fault is a broken wire in the harness near the front bumper, where flexing and road debris cause opens that a simple visual inspection can miss.
Some vehicles share the ambient temperature signal with the outside temperature display and climate control module over a data bus, so a communication fault elsewhere can set P0073 even when the sensor circuit itself is intact.
The ambient air temperature sensor is often confused with the intake air temperature sensor, but they serve different systems and set different codes, so confirm which sensor the scan tool is actually reading before testing.
On many vehicles the ambient temperature reading is used for battery charging strategy and remote start inhibit, so a high circuit code can cause seemingly unrelated electrical complaints that disappear once the sensor circuit is repaired.
A sensor that reads high only when the engine bay is hot can indicate a wiring issue that changes with temperature, so testing should include wiggle tests and resistance checks while the harness is warmed.

Can I keep driving with P0073?

The vehicle remains safe to drive because the ambient air temperature sensor does not affect engine operation or safety systems, but you should avoid relying on the outside temperature display or automatic climate control until the fault is repaired. Address the code reasonably soon to prevent related comfort and battery management features from being disabled.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.