What it means
Ambient air temperature sensor A signal voltage below the expected range — typically a short to ground.
At a glance
- Usually lights the check-engine light
How it works
Ambient air temperature sensor A is a temperature-dependent sensor whose signal voltage falls as its reported temperature rises. P0072 sets when the signal is below the expected range, commonly because the signal wire is shorted to ground or the sensor itself has an internal short; the display may then show an unusually high temperature.
Common causes
Most likely first.
- Signal wire shorted to ground
- Ambient temperature sensor internally shorted
- Damaged connector or wiring
- Corroded sensor terminals
Symptoms
- Check-engine light on
- Outside-temperature display may read unusually high
- Automatic climate control may behave unexpectedly
How to diagnose it
- Read the live sensor A temperature and compare it with ambient conditions to confirm the unusually high or implausible reading.
- Inspect sensor A's connector for corrosion, bent terminals, water, or a damaged plug.
- Check the signal wire for chafing or contact with ground, especially near the sensor and along the harness.
- Disconnect the sensor as directed by the manufacturer's procedure and check whether the circuit reading changes, helping distinguish a sensor short from a harness short.
- Test the sensor and circuit against the manufacturer's specification before replacing parts.
Common fixes
- Repair a signal wire shorted to ground.
- Clean or repair corroded or damaged sensor A connector terminals.
- Replace ambient temperature sensor A if it is internally shorted.
- Secure or reroute damaged wiring to prevent renewed contact with ground.
Can I keep driving?
The code usually does not affect engine operation, so driving is generally safe. The outside temperature display may read far too high and climate control may respond incorrectly.
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.