What Does P0070 Mean?
The ECM has detected a general malfunction in the ambient air temperature (AAT) sensor circuit. This sensor measures the outside air temperature and is used by the ECM for fuel mixture calculations, intake air density corrections, and climate control operation. The circuit may have an open, short, or intermittent condition. The driver may notice incorrect outside temperature display, slightly altered fuel economy, and possible A/C system issues.
Common Causes
35%
Failed ambient air temperature sensor (internal circuit failure)
28%
Damaged or corroded wiring/connector at the sensor (exposed to road elements)
18%
Sensor physically damaged by road debris or during bumper/grille work
12%
5V reference circuit fault shared with other sensors
7%
Water or debris intrusion in the sensor connector
Diagnostic Steps
1
Monitor the AAT sensor PID in live data. Compare the reading to actual ambient temperature. A reading stuck at -40°F (open circuit) or 280°F+ (short to ground) indicates a definitive sensor or wiring failure.
2
Locate the ambient air temperature sensor — typically mounted behind the front bumper, in the grille, or near the front of the bumper cover. Inspect for physical damage from road debris.
3
Disconnect the sensor and measure its resistance. At 70°F (21°C), a typical NTC thermistor reads 2,000-3,000 ohms. At 32°F (0°C), approximately 5,000-7,000 ohms. Compare to manufacturer spec.
4
Check the connector for corrosion, water, or road salt intrusion. This sensor location is extremely exposed to the elements. Clean and apply dielectric grease.
5
Verify the 5V reference and ground signals at the sensor connector with key on engine off. The 5V reference is shared with other sensors — a fault here may set additional codes.
Estimated Repair Cost
$30 - $200
Parts + labor, varies by vehicle and location
The ECM has detected a general malfunction in the ambient air temperature (AAT) sensor circuit. This sensor measures the outside air temperature and is used by the ECM for fuel mixture calculations, intake air density corrections, and climate control operation. The circuit may have an open, short, o...
The most common cause of P0070 (Ambient Air Temperature Sensor Circuit) is: Failed ambient air temperature sensor (internal circuit failure)
Typical repair costs for P0070 range from $30 to $200, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The ECM will use a default substitute value for ambient temperature. Fuel mixture calculations will be slightly less precise, and the outside temperature display will be incorrect. Climate control may not function optimally. Very low priority repair.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0070 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Management / Climate Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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