Powertrain, generic

P0E9E DC/DC Converter Current Sensor B Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0E9E flags the B current channel of a DC/DC converter reading above its ceiling: the raw signal lies above anything the sensor should output. With a Hall sensor whose zero lies mid-scale, this usually means the signal line touches the supply or the reference ground has opened. No manufacturer documents P0E9E publicly. Mercedes-Benz shows the same fault type on the first channel: on the EQB and G-Class, P0E5400 denotes a short to battery plus on the converter's current sensor A and shows up with red 12 V and HV warnings after a faulty wake-up; the workshop checks it with a buck-mode test of about 30 s in XENTRY and then resets the converter. Porsche calls the B channel current sensor 2 and has its low fault as P0E9D. A real overcurrent belongs to P0D33.

Likely causes

Sensor B signal shorted to supply voltage
Open reference ground of the current sensor
Converter in an error state after wake-up, cleared by reset

Symptoms

  • Red 12 V battery or HV warning
  • Converter stops supplying the 12 V network
  • Reduced drive power possible

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€60–2,500
Time0.3–5 h

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

Parts involved

dcdc current sensor bwiring harnessdcdc converter

Related codes

P0E9DP0E9BP0E9CP0E9FP0E54P0EA3

References: static.nhtsa.gov, static.nhtsa.gov, law.cornell.edu.