Powertrain, generic (extended)

P2A5A Alternative Fuel Vaporizer C Outlet Temperature Sensor Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

Vaporizer C is the third unit in a gas system that splits the conversion of liquid fuel over several heat exchangers, a layout that only makes sense for engines with very high gas demand. Each unit needs its own outlet sensor because a vaporizer that cannot keep up shows it first by a falling outlet temperature; patent US6755643B2 even uses an outlet sensor to shut a vaporizer down once the draw exceeds its capacity. P2A5A is the undirected circuit fault on the sensor of vaporizer C. No manufacturer documents this code, and public sources on three-vaporizer layouts are thin. CARB still requires circuit monitoring for such inputs. Depending on calibration, the module may limit gas operation or ignore unit C. Start with the connector and the sensor resistance.

Likely causes

Connector or wiring of the vaporizer C sensor faulty

Vaporizer C outlet sensor broken

Control module input for sensor C faulty

Symptoms

Check engine light, depending on calibration
Gas operation limited, less power at high load
Vehicle falls back to the other fuel

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€100–600

Time0.5–2.5 h

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

Parts involved

alt fuel vaporizer c outlet temp sensorwiring harnessafcm

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