What it means
The outlet temperature signal of alternative fuel vaporizer C does not match plausibility checks against fuel rail temperature and engine coolant temperature. Sensor drift.
At a glance
- Usually lights the check-engine light
- Affects emissions; the car can fail an emissions test
How it works
The AFCM checks the outlet temperature sensor on alternative-fuel vaporizer C against fuel-rail and engine-coolant temperatures for plausibility. This range/performance code sets when the signal is present but its temperature pattern does not agree with those reference readings, which can indicate sensor drift or poor sensor contact with the fuel path.
Common causes
Most likely first.
- Sensor characteristic drifted
- Sensor mounting displaced from fluid path
- Sensor element aged beyond calibration window
Symptoms
- Check-engine or alternative-fuel system warning light
- Rough running or hesitation on alternative fuel
- Reduced fuel economy
How to diagnose it
- Review freeze-frame data and live AFCM temperatures to establish the conditions when vaporizer C's outlet reading became implausible.
- With the vehicle cold, compare the vaporizer C outlet, fuel-rail, and coolant temperature readings and watch how they change during warm-up.
- Inspect the sensor mounting to confirm it is seated in its intended position in the fuel path.
- Check the vaporizer C sensor connector and wiring for corrosion, damage, or a poor connection that could distort the reading.
- If mounting and wiring are sound, test the sensor response against the manufacturer's specification and replace it if it drifts out of range.
Common fixes
- Re-seat the vaporizer C outlet-temperature sensor in its intended mounting position.
- Clean or repair a poor sensor connector or damaged wiring.
- Replace a vaporizer C outlet-temperature sensor that responds inaccurately or has aged beyond specification.
Can I keep driving?
You can generally drive if the engine remains smooth, but avoid relying on alternative-fuel operation if it hesitates or fuel economy worsens. Continued inaccurate temperature feedback can impair vaporization control and increase 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.