What it means
The alternative fuel tank C level sensor circuit signal is higher than expected.
At a glance
- Usually lights the check-engine light
How it works
The tank C level sensor signal tells the alternative-fuel control module how much fuel remains. This circuit-high code sets when the signal rises above its expected range, which can result from an open sensor or a signal shorted to battery voltage.
Common causes
Most likely first.
- Signal wire shorted to B+
- Open level sensor
- Connector pins corroded - high contact resistance
Symptoms
- Check-engine or alternative-fuel system warning light
- Alternative-fuel tank level or remaining range may be inaccurate
- Alternative-fuel operation may be limited
How to diagnose it
- Review freeze-frame and live tank C level data to confirm the high signal and note whether it is constant or occurs only under particular conditions.
- Inspect the sensor connector and harness for loose or corroded terminals, damaged insulation, and contact with a powered wire.
- Check the sensor connector for an open circuit or poor terminal contact, following the manufacturer's wiring information.
- Test the signal wire for a short to battery voltage and check continuity through the circuit with power safely isolated as specified.
- Compare sensor output and circuit readings with the manufacturer's specification to identify an open sensor or wiring fault.
Common fixes
- Secure the tank C sensor connector and correct loose or corroded terminals.
- Repair a signal wire shorted to battery voltage or damaged harness insulation.
- Repair an open circuit or poor connection in the sensor wiring.
- Replace the level sensor if it is open internally and fails the manufacturer's checks.
Can I keep driving?
The tank C level or range display may be inaccurate, and alternative-fuel operation may be limited. Treat the displayed level as unreliable and keep a conservative reserve until the circuit is repaired.
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.