P2A55 code meaning
Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit
Powertrain system Generic code P2Axx codes Check engine light
What P2A55 means
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.
P2A55 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P2A55
- Check engine light, depending on calibration
- Reduced power or gas mode limited
- Fall-back to the second fuel on dual-fuel engines
Common causes of P2A55
- Most likelyPlug or harness of the vaporizer B sensor damaged
- PossibleVaporizer B outlet sensor failed
- Less likelyFault in the sensor input of the control module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Alt fuel vaporizer b outlet temp sensorWiring harnessAfcm
What each part of P2A55 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 2 | Generic code (second SAE range): it means the same on every make. |
| A | Area: hybrid propulsion. |
| 55 | The exact fault in that area. |
What to do next
- Note P2A55 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P2A55
What does P2A55 mean?
P2A55 means "Alternative Fuel Vaporizer B Outlet Temperature Sensor Circuit". A second vaporizer appears where one heat exchanger cannot supply enough gas, for instance on large or heavy-duty engines. It is a generic code, so it means the same on every make.
Is it safe to drive with P2A55?
Drive gently and only to a workshop. With P2A55 the car can go into limp mode (reduced power) to protect itself.
Will P2A55 fail an emissions test?
Yes, it can. P2A55 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is P2A55 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P2A55 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.