What it means
The pressure sensor signal of alternative fuel tank B drops out or jumps intermittently. Loose connector or noisy ground.
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 tank B pressure sensor sends its signal to the AFCM so the module can monitor alternative-fuel tank pressure. P2A45 sets when that signal drops out or jumps unexpectedly rather than staying within a stable, plausible range. A loose connector, vibration-sensitive contact, or unstable ground reference can cause the erratic reading.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Check-engine light
- Alternative-fuel warning light
- Erratic tank pressure or fuel-level indication
How to diagnose it
- Save freeze-frame data and review AFCM live pressure data for tank B to see whether the reading jumps or drops out around the time the code sets.
- With the vehicle safely stationary, inspect the tank B sensor connector for an incomplete latch, loose pins, corrosion, or harness strain.
- Inspect the harness and ground reference for chafing, loose connections, or damage that could be affected by vibration.
- Monitor the sensor signal with the specified scan-tool or electrical test while gently checking accessible wiring for a dropout.
- If the wiring and ground remain stable, test the tank B sensor and its connector terminals for intermittent failure using the manufacturer’s procedure.
Common fixes
- Fully seat and secure the tank B pressure-sensor connector.
- Repair loose, corroded, or vibration-sensitive wiring and ground connections.
- Replace the tank B pressure sensor if it intermittently fails the specified test.
Can I keep driving?
The erratic tank reading may cause the AFCM to restrict or change alternative-fuel operation unexpectedly. If gasoline operation is normal, limit driving until diagnosed and avoid relying on the tank B 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.