Powertrain, generic

P0E54 DC/DC Converter Current Sensor A Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0E54 reports a current sensor A signal above the range the DC/DC converter accepts. Mercedes-Benz uses it explicitly: its bulletin LI54.10-P-079533, covering the EQB (series 243) and the G-Class including the electric G 580 (series 465), defines P0E5400 as a short to positive of the converter's current sensor A. It is one of up to four converter codes, with P0C3B00, P0E9700 and P0C4000, that appear after the converter wakes up incorrectly; drivers see a red 12 V battery message and HV warnings. Mercedes treats it as a state error rather than a broken part: the technician runs the buck mode in XENTRY for about 30 s, checks that output current settles from a high initial value, then clears the memory or resets the converter. The low-signal sibling is P0E53.

Likely causes

Converter stuck in a fault state after incorrect wake-up (Mercedes 243/465)
Signal line shorted to a supply voltage
Current sensor or converter electronics defective

Symptoms

  • Red 12 V battery message
  • White or yellow high-voltage system warnings
  • Reduced drive power

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 awiring harnessdcdc converter

Related codes

P0E51P0E52P0E53P0E55P0E9EP0C3B

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