P0072 low

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.

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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

Step-by-Step Diagnostic Procedure

  1. Read ambient air temp sensor value on scan tool. A reading near the maximum (e.g., 284F/140C) confirms a low circuit condition.

  2. Disconnect the sensor and measure resistance. A reading near 0 ohms indicates an internal short.

  3. Check wiring from sensor to PCM for shorts to ground. Inspect harness for chafing against body panels.

  4. With sensor disconnected, check that the scan tool reads the maximum default value. If it stays low, suspect PCM input.

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.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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