What it means
The control module checks whether the alternative fuel tank temperature sensor reading is plausible under current conditions. It sets this code when the reading is outside the expected range or does not change as expected.
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 provides a reading the control module uses to assess tank temperature. P01AB sets when that reading is implausible for current conditions or fails to change as expected, even though the circuit may not have a clear electrical open or short.
Common causes
Most likely first.
- Sensor reading drifted
- Sensor element aged beyond calibration window
- Sensor mounting loose - signal damping
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
- Record freeze-frame data and compare the reported tank temperature with ambient temperature and the vehicle's recent operating conditions.
- Watch live tank temperature data as the vehicle warms or cools to see whether it changes smoothly and plausibly.
- Inspect the sensor mounting and connector for looseness, damage, or a position that could prevent the sensor from sensing tank temperature correctly.
- Check the sensor wiring and connections for intermittent resistance or damage before judging the sensor's accuracy.
- Test the sensor response and mounting condition using the manufacturer's procedure and specification.
Common fixes
- Secure a loose tank temperature sensor in its proper mounting position.
- Repair damaged wiring or a poor connector contact.
- Replace a temperature sensor that drifts or responds incorrectly during testing.
- Clear the code and verify that the live reading behaves plausibly after repair.
Can I keep driving?
If the engine runs normally, limited driving may be possible, but the alternative-fuel system is operating with a questionable tank temperature reading. Avoid relying on the alternative-fuel system if a warning appears or running changes, and arrange diagnosis.
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.