P2A56 Alternative Fuel Vaporizer B Outlet Temperature Sensor Range/Performance

With two vaporizers fed by the same coolant, their outlet temperatures should behave alike, which gives the module a natural cross-check. P2A56 means the vaporizer B reading is electrically fine but out of line with that expectation, with the engine state or with its own history. The plausible window is wide: Westport's LNG patent gives vaporized fuel temperatures anywhere from about −20 °C to +80 °C depending on how the engine runs, so tests rely on comparisons rather than fixed values. Two causes look alike here: a drifting sensor, or vaporizer B really running colder because an air lock or kinked hose starves it of coolant. Feeling both coolant hoses settles it. The second case belongs to P2A8C. No manufacturer publishes P2A56 thresholds.

Likely causes

Symptoms

• Check engine light, depending on calibration
• Power drop under high load on gas
• Clear temperature gap between vaporizer A and B in live data

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, patents.google.com.