Powertrain, generic

P0E51 DC/DC Converter Current Sensor A Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0E51 is the general circuit fault of current sensor A in a DC/DC converter, the element that tells the converter's controller how many amps flow through its power stage. The code covers a signal path that is broken in a way the controller cannot sort into low, high or implausible. No manufacturer documents P0E51 publicly. The same sensor appears in Mercedes-Benz information LI54.10-P-079533 for the EQB and G-Class, where a short to positive is stored as P0E5400. Ford's hybrid summaries show what such a check looks at: at power-up the inductor current sensor of the boost converter must show less than 15 A offset and a raw signal between 4.5 and 6.0 V, though Ford files these faults under P0A11. CARB requires circuit checks on hybrid input components. Converter output is usually limited.

Likely causes

Current sensor inside the converter defective (usually not replaceable separately)
Loose, corroded or damaged sensor connection or harness
Fault on the converter control board or its sensor supply
Converter or hybrid control software needs an update

Symptoms

  • Hybrid or 12 V battery warning in the instrument cluster
  • 12 V battery is charged poorly or not at all
  • Reduced electric power or limited hybrid functions

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€100–2,500
Time0.5–5 h

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

Parts involved

dcdc current sensor awiring harnessdcdc converter

Related codes

P0E52P0E53P0E54P0E55P0E9B

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