What it means
Intermittent signal from alternative fuel tank A level sensor. 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 reports fuel level to the control module through an electrical circuit. P01B3 sets when that signal drops out or changes erratically instead of remaining consistent with the actual level, often as a loose connection or vibrating harness interrupts it.
Common causes
Most likely first.
- Connector loose or corroded
- Connector with intermittent contact under vibration
- Harness routed against vibrating component
Symptoms
- Check-engine light may come on intermittently
- Alternative-fuel level reading may fluctuate or drop out
- Fuel gauge or range estimate may be unreliable
How to diagnose it
- Save freeze-frame data and check whether tank A level data dropped out or changed abruptly when the code set.
- Watch the tank A level reading on a scan tool while gently moving the accessible sensor connector and harness to reproduce the fluctuation.
- Inspect the tank A connector for looseness or corrosion and check whether its harness rubs against or vibrates against nearby components.
- Check the signal wiring and connector continuity while moving the harness to locate an intermittent connection, following the manufacturer's wiring information.
- If the wiring and connector remain stable, test the tank A level sensor for an erratic output against the manufacturer's procedure.
Common fixes
- Secure a loose tank A sensor connector and repair corroded pins.
- Reroute and secure the tank A sensor harness away from rubbing or vibration.
- Repair an intermittent section of tank A sensor wiring.
- Replace the tank A level sensor if its output remains erratic with sound wiring.
Can I keep driving?
The tank A level reading may fluctuate or disappear, making the alternative-fuel gauge and range estimate unreliable. Do not depend on the display to gauge remaining fuel, and arrange diagnosis soon.
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.