What it means
The pressure sensor signal of alternative fuel tank C 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 AFCM watches the pressure signal from alternative fuel tank C for sudden dropouts or jumps. This code sets when the signal behaves erratically rather than remaining stable, often because the connector or ground loses contact with vibration.
Common causes
Most likely first.
- Sensor connector not seated
- Noisy ground reference
- Connector with intermittent contact under vibration
Symptoms
- Alternative-fuel system warning light, if equipped
- Fuel level or remaining range may fluctuate
- Alternative-fuel operation may be limited
How to diagnose it
- Check freeze-frame data and live tank C pressure for sudden jumps or dropouts, and note when they occur.
- Inspect the tank C sensor connector for incomplete seating, loose pins, corrosion, or strain on the harness.
- Check the sensor ground and signal connections against the manufacturer's wiring information.
- With the system monitored as directed by service information, gently move the accessible harness and connector to see whether the reading changes.
- If the circuit remains stable, test the tank C pressure sensor for intermittent output under the manufacturer's procedure.
Common fixes
- Seat and secure the tank C pressure-sensor connector.
- Repair loose pins, damaged wiring, or an unstable ground in the tank C circuit.
- Replace the pressure sensor if its signal drops out despite a stable circuit.
Can I keep driving?
Tank C pressure and fuel-range readings may fluctuate, and alternative-fuel operation may be limited. Avoid relying on the displayed range; stop if the vehicle develops fuel-system or drivability problems.
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.