Powertrain, generic (extended)

P2A7F Alternative Fuel Pump A Compression Stroke Valve Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

Hydraulically driven LNG pumps use solenoid valves to admit high-pressure oil to the drive side for the compression stroke and to vent it again for refilling. Caterpillar's patent US10060421B2 gives each of its six pumping elements, other counts being possible, a solenoid pilot that moves a spool between fill and drain positions; the controller sets timing and length of every stroke this way. P2A7F reports that pump A's compression stroke valve has an open or otherwise faulty control circuit. The valve then stays in its spring position and pump A no longer delivers. Which element or tank pump carries the letter A is not published, and neither is P2A7F itself. Check coil resistance and connector first.

Likely causes

Open wire or loose connector at valve A
Solenoid coil of valve A burnt open
Output stage in the control module faulty

Symptoms

  • Warning lamp on
  • Reduced LNG delivery and lower power
  • Gas pressure drops under 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 a compression stroke valvewiring harnessafcm

Related codes

P2A80P2A81P2A82P2A83P2A87

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