P0073 Code – Ambient Air Temperature Sensor Circuit High

The P0073 diagnostic trouble code (DTC) indicates that the ambient air temperature sensor circuit is reporting a voltage that is higher than expected.

The ambient air temperature (AAT) sensor measures the temperature of the outside air and sends this information to the engine control unit (ECU). This data is used by several systems in the vehicle, including:

• engine management

• climate control system

• cold start fuel adjustments

• dashboard outside temperature display

If the ECU detects that the signal voltage from the sensor is higher than the normal operating range, it will trigger the P0073 OBD2 code.

A high voltage signal typically means the sensor is reporting extremely hot temperatures, which usually indicates an electrical problem in the sensor circuit.

Symptoms of Code P0073

Common symptoms associated with the P0073 error code include:

• Check Engine light illuminated

• Outside temperature display showing extremely high values

• Climate control system behaving incorrectly

• Possible reduced fuel efficiency

• Incorrect engine management adjustments during cold starts

Drivers often notice the issue when the dashboard shows unrealistic outside temperatures, such as extremely high readings.

Common Causes of P0073

Typical causes include:

• Faulty ambient air temperature sensor

• Open circuit in the sensor wiring

• Damaged wiring harness

• Loose or disconnected sensor connector

• Corroded electrical connections

• ECU signal reference issues

Because the sensor is usually located behind the front grille or bumper, the wiring can sometimes become damaged due to road debris or moisture.

How Serious Is Code P0073

The P0073 code is generally considered a low severity issue.

The vehicle will typically continue to operate normally, but the issue may cause:

• inaccurate outside temperature readings

• incorrect climate control behavior

• less precise cold start fuel calculations

Although the vehicle remains drivable, repairing the issue ensures proper system operation.

How to Diagnose Code P0073

Diagnosis usually involves the following steps:

1. Scan the vehicle with an OBD2 diagnostic scanner

2. Check live data for the ambient air temperature value

3. Inspect the sensor location for damage

4. Check the wiring and connectors

5. Test sensor resistance with a multimeter

6. Verify the ECU reference voltage

If the sensor reading shows extremely high temperatures, the circuit likely has an open connection.

How to Fix Code P0073

Possible repair solutions include:

• replacing the ambient air temperature sensor

• repairing damaged wiring

• reconnecting loose connectors

• cleaning corroded electrical contacts

• clearing the code after repair

In most cases, replacing the sensor resolves the problem quickly.

Vehicles Commonly Affected by P0073

The P0073 trouble code may appear on many vehicles, including:

• Ford

• Chevrolet

• Volkswagen

• BMW

• Mercedes-Benz

• Toyota

• Nissan

• Hyundai

Any modern vehicle equipped with an ambient air temperature sensor connected to the ECU may trigger this code.

FAQ – P0073 Code

Can I drive with code P0073?

Yes. The vehicle can usually be driven safely, although some systems may not function optimally.

Why does the outside temperature show extremely high values?

This usually happens when the ambient air temperature sensor circuit reports a high voltage signal, often due to an open circuit or disconnected sensor.

Is replacing the ambient temperature sensor difficult?

No. In most vehicles the sensor is inexpensive and relatively easy to replace.