Ambient Air Temperature Sensor Circuit High
The P0073 code means the vehicle's onboard diagnostic system has detected: Ambient Air Temperature Sensor Circuit High. This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- easy
- Estimated cost
- $30 - $200 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- Dashboard temperature display reads extremely cold or shows dashes
- Automatic climate control defaults to manual mode
- Slight cold-start fueling inaccuracy
Probable Causes (Ranked by Likelihood)
- Open circuit in sensor wiring Very High
- Failed ambient air temperature sensor (open internally) High
- Disconnected or corroded sensor connector Moderate
- PCM internal pull-up resistor fault Low
Frequently Asked Questions
What does circuit high mean for P0073?
Circuit high means the PCM is seeing a voltage above the normal range. For this sensor, it usually indicates an open circuit where no signal is reaching the PCM.
Could a bumper replacement cause P0073?
Yes, if the ambient air temperature sensor was not reconnected after bumper removal, or if the wiring was damaged during the repair, P0073 will set.
Is P0073 an emissions failure?
Yes, the illuminated Check Engine Light will cause an emissions test failure regardless of the severity of the code.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read ambient air temp sensor on scan tool. A reading at the minimum (e.g., -40F/-40C) confirms a high circuit (open) condition.
-
Inspect the sensor connector behind the front bumper. Look for broken pins, corrosion, or a disconnected plug.
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Measure sensor resistance: an open reading (infinite ohms) confirms a failed sensor.
-
Check wiring continuity from the sensor connector to the PCM. Repair any open circuits found.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
Commonly Affected Vehicles
- 2010-2020 Hyundai Elantra
- 2012-2019 Kia Optima
- 2008-2018 Ford Focus
- 2011-2020 Chevrolet Malibu
Related Codes
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