P0073 Ambient Air Temperature Sensor Circuit High

P0073 indicates a high ambient air temperature sensor circuit. The signal is open, shorted to voltage, or reporting an unrealistically hot value.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not assume true high ambient temperature if the circuit is open or the front-end sensor is disconnected.

Symptoms of P0073

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0073

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Check ambient sensor signal voltage, ground, open circuits, short-to-voltage faults, connector fit, and sensor resistance.
Inspect front-end wiring for broken connectors, corrosion, bumper damage, grille repairs, and harness pulls near the sensor.
Compare the high reading with actual outside temperature and other temperature sensors after a cold soak.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.