P0E9E: DC/DC Converter Current Sensor B Circuit High

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.

High severity. Can I keep driving?If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

Symptoms

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

Most 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

What to check, in order

Start with the simplest. You can tick off each step.

Read the codes with a hybrid-compatible scanner and write down the freeze frame data
Check the sensor's ground and make sure the signal wire is not receiving voltage from another circuit.
Make sure the battery cooling air intake is clean
Check the 12 V auxiliary battery, which can also trigger warnings
Leave any high-voltage measurements to a specialized repair shop

Good to know

It can trigger limp mode.
It affects emissions.

What each character of P0E9E means

P: Powertrain: engine and transmission
0: Generic code: same on every make
E: Subsystem depends on the code range
9E: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0E9E?

If the car still runs, drive as little as possible and go to a specialized repair shop. Do not touch the orange cables: they carry high voltage.

What causes code P0E9E?

The most common causes are: 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.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.