Powertrain, generic (extended)

P2A7D Alternative Fuel Hydraulic Pressure Sensor Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A7D means the hydraulic pressure sensor reads above its upper limit, typically because the signal line is touches the reference or battery supply, or its ground connection is broken. Unlike P2A7C, this fault is obvious at once: a full-scale reading while the pump is idle or retracting contradicts every other input. Caterpillar's patent notes that a sensor in the return line can also serve to shift the directional valve, though the supply-side sensor is preferred at high hydraulic pressure; on systems that use the return value, a falsely high reading could therefore upset stroke switching. No manufacturer publishes P2A7D. See whether the reading changes with the plug disconnected, and test the ground circuit.

Likely causes

Sensor ground open or high resistance
Signal line shorted to reference or battery voltage
Sensor output stuck at maximum

Symptoms

  • Warning lamp on
  • Erratic or stopped pump strokes
  • Reduced power on gas

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

P2A7AP2A7BP2A7CP2A7EP2A78

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