Powertrain, generic

P0E9B DC/DC Converter Current Sensor B Circuit

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P0E9B opens the series for the second current measurement of a DC/DC converter, sensor B. It covers a signal that is absent or unusable on the electrical level and that the controller cannot classify as low, high or implausible; those cases follow as P0E9C to P0E9F. No manufacturer documents P0E9B itself. Porsche confirms what sensor B is in practice: on the Taycan the high-voltage power electronics name the same channel current sensor 2 and store its short to ground as P0E9D00. Ford's hybrid summary shows what a current input check looks at, an offset below 15 A at power-up and a raw value kept inside 4.5-6.0 V. CARB makes circuit monitoring of such inputs mandatory. Without the reading the converter usually derates.

Likely causes

Fault in the converter's internal current sensing
Connector or wiring fault on the sensor B path
Control software misjudging the signal

Symptoms

  • High-voltage or 12 V system warning
  • Converter output reduced, 12 V battery charged less
  • Possibly reduced drive power

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 bwiring harnessdcdc converter

Related codes

P0E9CP0E9DP0E9EP0E9FP0E51P0EA0

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