Ambient Air Temperature Sensor Circuit High Input
The P0073 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the ambient air temperature (AAT) sensor that is higher than the expected range, typically above 4.5 volts. This sensor measures outside air temperature and is used for HVAC control and other engine management functions. A high input suggests an open circuit, short to voltage, or a faulty sensor.
01. Most Common Causes
- Faulty ambient air temperature sensor
- Open or shorted wiring in the sensor circuit
- Corroded or damaged connector
- ECM issue (rare)
02. Symptoms You Will Notice
- Incorrect outside temperature display
- HVAC system not working properly
- Check Engine Light illuminated
- Possible poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect the AAT sensor and wiring for damage or corrosion.
Step 3: Test sensor voltage and resistance with a multimeter; compare to specifications.
Step 4: Check for shorts to voltage or ground in the wiring harness.
Step 5: Replace sensor if faulty; repair wiring if necessary.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
Yes, but the HVAC system may not work correctly and fuel economy could be slightly affected. It's best to diagnose and repair soon.
How much does it cost to fix?▼
Typically $50-$150 for parts and labor, depending on sensor location and labor rates.