Powertrain, generic (extended)

P2A50 Alternative Fuel Vaporizer A Outlet Temperature Sensor Circuit

Check engine lightOn

EmissionsRelevant

Drive cycleNot required

Limp modePossible

A vaporizer, often called reducer or converter on LPG systems, turns liquid gas into vapour with heat taken from the engine coolant. The sensor in P2A50 sits on the outlet side of vaporizer A and tells the control unit whether that unit is warm enough. Patent US7073489B2 explains why this matters: with too little heat the liquid does not fully evaporate and can block the regulator jet. P2A50 covers any fault in this sensor circuit that the module cannot classify as low or high. No vehicle manufacturer documents P2A50 publicly; aftermarket controllers such as AC STAG show the same problem as a missing or shorted reducer temperature sensor. Until the circuit works again, the system will usually stay on or return to petrol.

Likely causes

Plug or wiring of the vaporizer A outlet sensor faulty

Outlet temperature sensor of vaporizer A defective

Input stage of the gas control module disturbed

Symptoms

Check engine light, depending on calibration
Vehicle stays on petrol or switches back from gas
Gas mode indicator flashes or stays off

Repair estimate

DifficultyMediumWorkshop job

Parts and labour€80–450

Time0.5–2 h

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

Parts involved

alt fuel vaporizer a outlet temp sensorwiring harnessafcm

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