Powertrain, generic (extended)

P2A7E Alternative Fuel Hydraulic Pressure Sensor Circuit Intermittent/Erratic

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2A7E flags a hydraulic pressure sensor signal that breaks up or spikes briefly, then recovers before the low or high checks of P2A7C and P2A7D mature. Pressure in a pump drive pulses with every stroke anyway, so the controller has to tell genuine pressure swings from electrical noise; what it treats as erratic is a change faster than the hydraulics can produce, or a signal vanishing between strokes. Cold, damp surroundings close to the cryogenic tank, loose terminals and wiring rubbing on hydraulic hoses are typical causes. As long as the fault comes and goes, fuel delivery usually continues, but stroke timing may wander. No manufacturer documents P2A7E. Record the signal while moving the harness and compare it with the P2A75 sensor trace.

Likely causes

Loose terminal in the sensor connector
Wiring rubbing on hydraulic hoses
Condensation or ice near the cryogenic tank

Symptoms

  • Warning lamp that comes and goes
  • Uneven pump cycling or brief power dips

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–700
Time1–4 h

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

Parts involved

alt fuel hyd pressure sensorwiring harnessafcm

Related codes

P2A7AP2A7BP2A7CP2A7DP2A79

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