What it means
The AFCM detects a generic fault on the alternative fuel temperature sensor. Fuel viscosity and density compensation cannot be applied reliably.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The AFCM uses the alternative fuel temperature sensor to account for changes in fuel temperature when controlling the system. This code sets when the module detects a fault in that sensor circuit and cannot rely on its temperature input.
Common causes
Most likely first.
- Temperature sensor failed
- Wiring or connector fault
Symptoms
- Check-engine or alternative-fuel system warning light
- Alternative-fuel operation may be limited
- Reduced fuel economy
How to diagnose it
- Record freeze-frame data and compare live alternative-fuel temperature with ambient and fuel-rail temperatures when the vehicle is cold.
- Inspect the temperature-sensor connector and wiring for looseness, corrosion, heat damage, or chafing.
- Use the manufacturer's wiring information to check the sensor's reference supply, ground, and signal circuit.
- Measure the signal at the sensor and AFCM to find an open, short, or poor connection.
- If the circuit checks out, test the alternative fuel temperature sensor to the manufacturer's specification.
Common fixes
- Reconnect or clean the alternative fuel temperature-sensor connector.
- Repair damaged wiring or a poor ground in the temperature-sensor circuit.
- Replace the alternative fuel temperature sensor if it fails the manufacturer's test.
Can I keep driving?
If the vehicle runs normally, a short drive may be possible, but alternative-fuel operation may be limited and fuel economy may worsen. Follow the vehicle's fuel-system warnings and avoid using alternative fuel if 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.