Powertrain, generic (extended)

P2A71 Alternative Fuel Hydraulic Fuel Pump Select Valve Control Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2A71 concerns the function of the hydraulic fuel pump select valve rather than its wiring: the circuit is intact, but the system does not respond as expected after a switch command. In Westport's design the controller links the hydraulic pressure it measures to whichever pump the selector valve should be feeding; if the pressure pattern does not match the commanded pump, or the empty-tank logic sees no change after switching, the valve is probably sticking or leaking internally. Contaminated hydraulic oil, a worn spool or a weak solenoid are typical. Caterpillar's patent describes a related directional valve whose actuator is shifted once pressure sensors detect the stroke end. No manufacturer publishes P2A71 or its limits.

Likely causes

Valve spool sticking due to contaminated hydraulic oil
Worn valve leaking internally, flow reaches both pumps
Solenoid force too low, for example from low supply voltage

Symptoms

  • Check engine light on
  • Tank changeover does not happen or happens late
  • Uneven LNG levels between tanks

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€200–1,800
Time1.5–5 h

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

Parts involved

alt fuel hyd pump select valvewiring harnessafcm

Related codes

P2A70P2A72P2A73P2A74P2A76

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