What it means
The AFCM detects a generic fault on the outlet temperature sensor of alternative fuel vaporizer B. 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 B prepares fuel for delivery to the engine, and its outlet-temperature sensor reports the temperature of fuel leaving that vaporizer to the 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 from vaporizer B.
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 P2A55 is current or stored, along with any related alternative-fuel codes.
- Compare vaporizer B 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 B'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 B's outlet-temperature sensor against the manufacturer's specification and replace it if it fails.
Common fixes
- Reconnect or clean the vaporizer B outlet-temperature sensor connector and repair damaged wiring.
- Repair an open, short, or poor ground in the vaporizer B sensor circuit.
- Replace the vaporizer B 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 B 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.