What it means
Alt fuel tank A level 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
How it works
The alternative fuel tank A level sensor sends a fuel-level signal to the control module. P01B2 sets when the module detects a signal above its expected electrical range, a condition that can result from an open signal path or an unintended connection 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 level reading may be inaccurate or unavailable
- Fuel gauge or range estimate may be unreliable
How to diagnose it
- Save freeze-frame data and check whether tank A level data is unusually high, fixed, or unavailable while the fault is present.
- Inspect the tank A sensor connector and harness for a disconnected or backed-out pin, corrosion, broken wiring, or insulation damage near a power source.
- Monitor tank A level data while gently moving the accessible harness to see whether the reading changes as a loose connection or damaged wire moves.
- Use the manufacturer's wiring information to check for an open in the tank A sensor signal circuit and for an unintended connection to battery voltage.
- If the circuit checks out, test the tank A level sensor and its supply and ground against the manufacturer's specification.
Common fixes
- Reconnect or repair a loose tank A sensor connector and its pins.
- Repair an open signal wire or wiring that is shorted to a power source.
- Replace the tank A level sensor if it fails the manufacturer's test.
Can I keep driving?
The alternative-fuel level display and range estimate may be inaccurate or unavailable, so plan refuelling using a reliable method. Have the circuit checked soon, especially if the vehicle has poor running or reduced power.
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.