Ambient Air Temperature Sensor Circuit Low
The P0072 code means the vehicle's onboard diagnostic system has detected: Ambient Air Temperature Sensor Circuit Low. 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 high
- HVAC may default to a fixed temperature mode
- Fuel trim may shift slightly rich at cold start
Probable Causes (Ranked by Likelihood)
- Short to ground in sensor wiring Very High
- Failed ambient air temperature sensor (shorted internally) High
- Corroded sensor connector pins Moderate
- PCM input circuit fault Low
Frequently Asked Questions
What does circuit low mean for P0072?
Circuit low means the PCM is receiving a voltage signal below the normal operating range, typically indicating a short to ground or a failed sensor.
Can a damaged wire cause P0072?
Yes, a wire that has chafed through its insulation and contacts the vehicle body or another ground source will cause a low circuit reading.
How much does it cost to fix P0072?
The ambient air temperature sensor itself costs $10-$40. Labor is typically $50-$150 since the sensor is usually easy to access behind the bumper.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Read ambient air temp sensor value on scan tool. A reading near the maximum (e.g., 284F/140C) confirms a low circuit condition.
-
Disconnect the sensor and measure resistance. A reading near 0 ohms indicates an internal short.
-
Check wiring from sensor to PCM for shorts to ground. Inspect harness for chafing against body panels.
-
With sensor disconnected, check that the scan tool reads the maximum default value. If it stays low, suspect PCM input.
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 Ford F-150
- 2012-2019 Nissan Altima
- 2008-2018 Chevrolet Silverado
- 2011-2020 Toyota Camry
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