What it means
The alternative fuel temperature sensor signal 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
How it works
The AFCM watches the alternative fuel temperature signal for sudden dropouts or jumps. This code sets when the reading becomes erratic, often because the connector, signal, or ground loses contact as the vehicle vibrates.
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 operation may be intermittent
- Reduced fuel economy
How to diagnose it
- Check freeze-frame data and live alternative-fuel temperature for abrupt jumps or dropouts, noting when they occur.
- Inspect the temperature-sensor connector for incomplete seating, loose pins, or corrosion.
- Check the sensor ground and signal wiring for damage and compare the circuit with the manufacturer's wiring information.
- While monitoring live data as service information directs, gently move the accessible harness and connector to see whether the reading changes.
- If the circuit stays stable, test the temperature sensor for intermittent output using the manufacturer's procedure.
Common fixes
- Seat and secure the alternative fuel temperature-sensor connector.
- Repair loose pins, damaged signal wiring, or an unstable ground.
- Replace the temperature sensor if its output remains erratic with a sound circuit.
Can I keep driving?
Alternative-fuel operation may be intermittent and fuel economy may suffer while the temperature reading drops out. Avoid using alternative fuel if the system warning appears or operation becomes rough.
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.