Powertrain, generic (extended)

P2A83 Alternative Fuel Pump B Compression Stroke Valve Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A83 reports an open or otherwise faulty control circuit at the compression stroke valve of alternative fuel pump B. Whether a second pump exists depends on the layout: in Westport's patent US8726785B2, two LNG vessels each carry their own hydraulically driven pump, while Caterpillar's multi-element pump splits one unit into several separately switched elements. Either way, pump B's valve no longer admits drive oil, and its share of LNG delivery is lost. On a two-tank truck this can leave fuel stranded in the tank that pump B serves. The meaning of the letter B is not public, and no manufacturer documents P2A83. Where the valves are identical, swapping a connector with a neighbour shows whether the fault follows the coil.

Likely causes

Open wire or loose connector at valve B
Solenoid coil of valve B open
Output stage for valve B faulty

Symptoms

  • Warning lamp on
  • LNG in one tank cannot be used
  • Reduced power under high load

Repair estimate

DifficultyHardWorkshop job
Parts and labour€150–1,500
Time1–4 h

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

Parts involved

alt fuel pump b compression stroke valvewiring harnessafcm

Related codes

P2A84P2A85P2A86P2A7FP2A87

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