What it means
The AFCM detects a generic fault on the outlet temperature sensor of alternative fuel vaporizer A. 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
Alternative fuel vaporizer A prepares the fuel for delivery to the engine, and its outlet temperature sensor reports the temperature of the fuel leaving that vaporizer to the alternative fuel control module (AFCM). The AFCM monitors the sensor circuit for electrical faults; this code sets when it detects a general circuit problem that prevents reliable temperature feedback.
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
- Use a scan tool to record freeze-frame data and check whether P2A50 is current or stored, along with any related alternative-fuel codes.
- Compare vaporizer A outlet temperature data with fuel-rail and coolant temperatures from a cold start, then watch for a missing or implausible reading as the engine warms.
- Inspect vaporizer A's outlet-temperature sensor connector and nearby wiring for looseness, corrosion, damage, or contact with hot or moving parts.
- Check the sensor circuit wiring and connections for continuity, shorts, and a sound ground reference using the manufacturer's wiring information.
- If the wiring checks pass, test vaporizer A's outlet-temperature sensor against the manufacturer's specification and replace it if it fails.
Common fixes
- Reconnect or clean the vaporizer A outlet-temperature sensor connector and repair damaged wiring.
- Repair an open, short, or poor ground in the vaporizer A sensor circuit.
- Replace the vaporizer A outlet-temperature sensor if it fails testing.
Can I keep driving?
If the vehicle runs normally on its conventional fuel, avoid relying on alternative-fuel operation if it causes hesitation or rough running. Continued use with unreliable vaporizer A temperature feedback can impair alternative-fuel 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.