Powertrain, generic (extended)

P2A88 Alternative Fuel Pump C Compression Stroke Valve Control Circuit Range/Performance

Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible

P2A88 reports that the compression stroke valve of pump C works electrically but its effect does not match the command. In a sequenced multi-element pump, each activation should add a similar amount of pressure to the gas accumulator or rail; an element that keeps falling short, or whose share fluctuates, stands out against its neighbours. Since Caterpillar's patent sets stroke length through the duration of the command, a spool that opens late shortens pump C's stroke without any wiring fault. Deposits on the spool, a partly blocked oil passage or worn cryogenic seals are plausible causes. Because the other elements keep running, the driver may notice little apart from the warning lamp. No manufacturer publishes P2A88 or its thresholds.

Likely causes

Deposits making the spool of valve C open late
Partly blocked oil passage to element C
Worn cryogenic seals on element C

Symptoms

  • Warning lamp after several drive cycles
  • Little noticeable change in driving

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€200–2,500
Time1.5–6 h

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

Parts involved

alt fuel pump c compression stroke valvewiring harnessafcm

Related codes

P2A87P2A89P2A8AP2A80P2A84

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