Powertrain, generic (extended)

P2A7A Alternative Fuel Hydraulic Pressure Sensor Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A7A is the general circuit fault of the alternative fuel hydraulic pressure sensor, a measuring point that the code list keeps apart from the hydraulic pump pressure sensor of P2A75. Where it sits is not defined publicly, and no manufacturer documents the split. Patents for hydraulically driven LNG pumps show the candidates: Caterpillar's US9228574B2 places one sensor in the supply line and another in the return line to the reservoir, while Westport's US8726785B2 suggests one sensor per side of the drive piston when pressure is taken at the drive unit. P2A7A is stored when the signal is faulty but fits neither a clear low nor a clear high case. Pump control then lacks one input and may restrict LNG delivery. P2A7C and P2A7D name low and high.

Likely causes

Damaged connector or harness at the hydraulic sensor
Hydraulic pressure sensor faulty
Fault in a sensor reference or ground shared with other sensors

Symptoms

  • Warning lamp on
  • Reduced LNG delivery or power limitation

Repair estimate

DifficultyHardWorkshop job
Parts and labour€100–900
Time1–3 h

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

Parts involved

alt fuel hyd pressure sensorwiring harnessafcm

Related codes

P2A7BP2A7CP2A7DP2A7EP2A75

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