What it means
The AFCM detects a generic fault on the outlet temperature sensor of alternative fuel vaporizer C. Vaporization control cannot be tuned reliably.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The alternative-fuel control module (AFCM) uses the outlet temperature sensor on vaporizer C to track the temperature of fuel leaving that vaporizer. This generic circuit fault sets when the module detects an electrical problem that prevents it from trusting the sensor signal.
Common causes
Most likely first.
- Temperature sensor failed
- Wiring or connector fault
Symptoms
- Check-engine or alternative-fuel system warning light
- Rough running or hesitation on alternative fuel
- Alternative-fuel operation may be limited
How to diagnose it
- Read the freeze-frame and AFCM data to see when the vaporizer C outlet-temperature fault occurred and whether alternative-fuel operation was active.
- Inspect the vaporizer C outlet-temperature sensor connector and nearby wiring for looseness, corrosion, chafing, or heat damage.
- Check the sensor and harness connections for continuity and shorts using the vehicle wiring diagram and manufacturer's specification.
- Compare the sensor's live reading with fuel-rail and coolant temperatures from a cold start through warm-up to identify an implausible or missing signal.
- If the wiring checks out, test the vaporizer C outlet-temperature sensor against the manufacturer's specification and replace it if it fails.
Common fixes
- Reconnect and secure the vaporizer C outlet-temperature sensor connector.
- Repair damaged wiring or corroded terminals in the sensor circuit.
- Replace a vaporizer C outlet-temperature sensor that fails testing.
Can I keep driving?
If the engine runs normally on another available fuel, drive gently and monitor for hesitation; alternative-fuel operation may be restricted. Avoid relying on alternative fuel until the fault is repaired, since poor vaporization control can worsen running and emissions.
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.