P2A55Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- A second vaporizer appears where one heat exchanger cannot supply enough gas, for instance on large or heavy-duty engines. On LNG trucks the job is harder still: Westport's patent CA2862664C starts from liquid near −160 °C, heats it with engine coolant and places a gas temperature sensor downstream of the exchanger to choose how the coolant flows. P2A55 reports a circuit fault of the outlet sensor on vaporizer B that the module cannot sort into low or high. For heavy-duty alternative fuel engines from model year 2018, CARB section 1971.1 lets each maker submit its own monitoring plan, which helps explain why public code lists are scarce; none documents P2A55. The intact sensor on vaporizer A helps as a comparison while tracing plug and harness of B.
- What you may notice
- Check engine light, depending on calibration
- Reduced power or gas mode limited
- Fall-back to the second fuel on dual-fuel engines
- Likely causes
- LikelyPlug or harness of the vaporizer B sensor damaged
- PossibleVaporizer B outlet sensor failed
- RareFault in the sensor input of the control module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €100 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.