What it means
The control module monitors the alternative fuel tank temperature sensor circuit. It sets this code when it detects an electrical fault, such as a signal outside the expected circuit range.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The alternative-fuel tank temperature sensor reports tank temperature to the control module through an electrical circuit. P01AA indicates a circuit fault, such as an open or short, so the module may not receive a usable temperature signal.
Common causes
Most likely first.
- Temperature sensor failure
- Open or short in sensor wiring
- Loose, damaged, or corroded connector
Symptoms
- Check-engine light on
- Alternative-fuel tank temperature reading may be inaccurate or unavailable
- Alternative-fuel system warning may appear
How to diagnose it
- Scan for freeze-frame data and compare the tank temperature reading with ambient temperature after the vehicle has been parked long enough to cool or warm.
- Inspect the tank temperature sensor connector and accessible harness for loose fit, corrosion, moisture, or physical damage.
- Check the sensor signal, supply, and ground wiring for opens or shorts using the vehicle wiring diagram.
- Measure circuit continuity and connector terminal condition, checking for a fault that changes when the harness is moved.
- Test the tank temperature sensor according to the manufacturer's specification before replacing it.
Common fixes
- Reconnect and secure a loose tank temperature sensor connector.
- Clean or replace corroded terminals and repair damaged wiring.
- Repair an open or short in the sensor circuit.
- Replace the tank temperature sensor if it fails its specified electrical test.
Can I keep driving?
If the vehicle runs normally and has no fuel-system warning requiring you to stop, a short trip may be possible, but the alternative-fuel system may not have a reliable tank temperature reading. Arrange diagnosis soon and stop if a fuel-system warning or abnormal running develops.
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.