P0E31: DC/DC Converter Voltage Sensor A Circuit

P0E31 is the general circuit code of voltage sensor A in a DC/DC converter, the measurement the converter or its controller uses to regulate output voltage. It is used for electrical faults that do not fit the low, high or erratic categories. P0E31 itself is not documented publicly by any manufacturer. GM's 2025 engine tables use the neighbouring codes for the same sensor in a converter that steadies the 12 V supply during engine auto-starts: P0E33 below 1 V, P0E34 above 28 V, P0E32 for implausible values. FCA names sensor A as voltage sensor 1 on the 2021 Ram 1500 eTorque. CARB wants open circuits and out-of-range signals of such inputs reported separately where feasible. With a lost voltage signal the converter tends to stop or run in a fallback mode.

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

Warning light and possibly 12 V battery warning
Engine auto-stop disabled or reduced 12 V supply

Most likely causes

Voltage measurement inside the DC/DC converter failed
Wiring or connector fault on the converter
Poor ground connection of the converter

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
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

Repair difficulty: hard
It affects emissions.

What each character of P0E31 means

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

Frequently asked questions

Can I keep driving with code P0E31?

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 P0E31?

The most common causes are: voltage measurement inside the DC/DC converter failed; wiring or connector fault on the converter; poor ground connection of the converter.

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.