What it means
The level sensor signal of alternative fuel tank B drops out or jumps intermittently. Loose connector or vibration-sensitive contact.
At a glance
- Usually lights the check-engine light
How it works
The AFCM watches the level signal from alternative fuel tank B for sudden dropouts or jumps. This intermittent/erratic code sets when the signal changes inconsistently, often because a loose connector or vibration-sensitive contact interrupts the circuit.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Check-engine or alternative-fuel system warning light
- Alternative-fuel tank level or remaining range may fluctuate
- Alternative-fuel operation may be limited
How to diagnose it
- Review freeze-frame and fault records to identify the conditions when tank B's level signal dropped out or jumped.
- Observe the live tank B level reading while gently moving the accessible sensor connector and harness to check for abrupt changes.
- Inspect the connector seating, terminals, ground reference, and harness routing for looseness, corrosion, chafing, or vibration damage.
- Use the wiring diagram to check the signal and ground circuits for intermittent continuity or unwanted shorts while flexing the harness.
- If the connections remain stable, test the tank B level sensor against the manufacturer's specification and replace it if its output is erratic.
Common fixes
- Fully seat and secure the tank B level-sensor connector.
- Repair a loose, corroded, or vibration-damaged terminal or wire.
- Restore a sound sensor ground connection.
- Replace the tank B level sensor if its signal remains erratic with a sound harness.
Can I keep driving?
You can generally drive if the vehicle runs normally, but treat tank B's level and range display as unreliable and refuel early. If the reading drops out, the AFCM may limit alternative-fuel operation.
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.