What it means
Ambient air temperature sensor A signal voltage above the expected range — typically open circuit (broken wire or sensor) or short to power.
At a glance
- Usually lights the check-engine light
How it works
Ambient air temperature sensor A reports outside-air temperature to the vehicle’s control module, and may also supply the climate-control display. The module flags P0073 when the sensor signal voltage is higher than its expected range, which can happen if the circuit is open or the signal is shorted to power.
Common causes
Most likely first.
- Open signal wire or loose connector
- Ambient temperature sensor internally open
- Signal wire shorted to voltage
- Corroded or damaged sensor terminals
Symptoms
- Check-engine light on
- Outside-temperature display may read unusually low
- Automatic climate control may behave unexpectedly
How to diagnose it
- Record freeze-frame data and compare the scan-tool ambient-temperature reading with the actual outside temperature after the vehicle has sat long enough to stabilize.
- Inspect sensor A and its connector for loose fit, corrosion, water, or damaged terminals, since a poor connection can leave the signal circuit open.
- Trace the sensor wiring for breaks, stretched sections, or contact with power wiring that could cause a short to voltage.
- With the wiring diagram, check signal and reference circuits for continuity and shorts to power, following the manufacturer's test procedure.
- If the wiring and connections pass, test sensor A against the manufacturer's specification and replace it if it is internally open.
Common fixes
- Reconnect and secure a loose sensor A connector.
- Clean or repair corroded or damaged terminals.
- Repair an open or power-shorted section of wiring.
- Replace ambient air temperature sensor A if it fails testing.
Can I keep driving?
Usually the vehicle remains driveable, but the outside-temperature display or automatic climate control may be unreliable. Avoid relying on the displayed temperature for decisions about icy conditions.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.