What it means
Voltage on the pressure sensor signal line of alternative fuel tank B is above the expected window. Wire shorted to B+ or sensor open.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
- The engine or gearbox may go into limp mode
How it works
The AFCM monitors the signal from the alternative-fuel tank B pressure sensor. P2A44 sets when the signal rises above its expected electrical window, which can result from a wire shorted to battery voltage, an open sensor, or poor connector contact. The AFCM may then display an unreliable tank reading or limit alternative-fuel operation.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open pressure sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine light
- Alternative-fuel warning light
- Inaccurate tank pressure or fuel-level indication
How to diagnose it
- Save freeze-frame data and check AFCM live data for the tank B pressure value and whether it is fixed or implausibly high.
- Inspect the tank B sensor connector and harness for a signal wire contacting battery voltage, damaged insulation, corrosion, or loose pins.
- Check connector contact and sensor terminals for corrosion or an open connection.
- Test the signal circuit for a short to voltage and check continuity according to the manufacturer’s wiring diagram and specification.
- If wiring and connections pass, test the tank B pressure sensor for an internal open using the specified procedure.
Common fixes
- Repair a tank B pressure-sensor signal wire shorted to battery voltage.
- Restore proper connector contact or repair an open in the sensor wiring.
- Replace the tank B pressure sensor if it fails the specified tests.
Can I keep driving?
The displayed tank B pressure or fuel level may be inaccurate, and the AFCM may limit alternative-fuel operation. If gasoline operation is normal, drive only as needed for diagnosis and do not rely on the alternative-fuel indication.
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.