What it means
Alt fuel tank temp sensor signal voltage above expected range. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
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 sends a voltage signal to the control module. P01AD sets when that signal is above the expected electrical range, which can occur with an open signal circuit or a supply wire shorted to battery voltage.
Common causes
Most likely first.
- Signal wire open
- Connector pins corroded - high contact resistance
- Supply wire pinched against B+ source
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
- Use a scan tool to save freeze-frame data and note whether the reported tank temperature is implausible while the code is present.
- Inspect the sensor connector for corrosion, moisture, backed-out pins, and a poor fit, then examine the harness for chafing.
- Move the harness gently while watching live tank temperature data to identify a connection that changes with movement.
- Check the signal wire for an open and the supply wiring for a short to battery voltage using the wiring diagram.
- Test the sensor output and circuit connections against the manufacturer's specification if the wiring checks out.
Common fixes
- Repair an open in the tank temperature sensor signal wire.
- Replace corroded or backed-out connector terminals.
- Repair a supply wire short to battery voltage and protect the harness from chafing.
- Replace the sensor if it fails testing with correct wiring and connections.
Can I keep driving?
A short drive may be possible if there are no other warnings and the vehicle runs normally, but the control module may not have a trustworthy tank temperature reading. Avoid continued use if an alternative-fuel warning appears or the engine behaves abnormally.
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.