What it means
The alternative fuel tank C level sensor circuit signal is intermittent or erratic.
At a glance
- Usually lights the check-engine light
How it works
The tank C level sensor signal changes as the alternative-fuel level changes, and the control module expects it to remain electrically stable. This intermittent/erratic code sets when that signal drops out or fluctuates unexpectedly, often as a loose contact or ground problem changes with vibration.
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 data and live tank C level readings for sudden jumps or dropouts, and note whether they coincide with bumps or vehicle movement.
- Inspect the sensor connector for a plug that is not fully seated, corrosion, or terminals that have lost tension.
- Examine the tank C sensor wiring and ground for chafing, loose attachment, or damage that could move with vibration.
- With the scan tool monitoring the signal, gently move the accessible harness and connector to check for a reproducible dropout.
- Test the sensor ground and signal circuit for intermittent continuity or resistance changes against the manufacturer's specification.
Common fixes
- Fully seat and secure the tank C sensor connector.
- Clean or repair loose, corroded, or damaged connector terminals.
- Repair chafed wiring or secure a loose ground connection.
- Replace the sensor if its output remains erratic after circuit and connection faults are corrected.
Can I keep driving?
The tank C level and range may fluctuate, and the system may limit alternative-fuel operation. Avoid relying on the displayed level; if fuel operation becomes inconsistent, switch fuels or stop in a safe place.
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.