P0C3E: DC/DC Converter Temperature Sensor B Range/Performance

P0C3E flags DC/DC converter temperature sensor B as electrically valid but implausible, for instance when it disagrees with sensor A or with what the converter load should produce. FCA uses it on the 2021 Ram 1500 with the 3.6 litre eTorque mild hybrid under the name temperature sensor 2 performance. Bulletin 08-037-21 reflashes the hybrid control processor and changes P0C3E, together with P0C39 for sensor 1, from a two-trip to a one-trip code, so one failed test can light the MIL. CARB requires rationality checks for converter inputs. Typical causes are a drifting element, poor thermal contact or outdated software. Circuit faults of sensor B are reported as P0C3D, P0C3F or P0C40; a converter that is really too hot sets P0D32 instead.

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

MIL, after one trip with updated Ram software
Mild hybrid assist or 12 V supply reduced

Most likely causes

Outdated hybrid control software (Ram 1500 eTorque, bulletin 08-037-21)
Sensor B drifting or with poor thermal contact
Uneven converter cooling making sensors A and B disagree

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
Compare the reading with other engine data while varying the engine speed.
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 P0C3E means

P: Powertrain: engine and transmission
0: Generic code: same on every make
C: Subsystem depends on the code range
3E: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0C3E?

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 P0C3E?

The most common causes are: outdated hybrid control software (Ram 1500 eTorque, bulletin 08-037-21); sensor B drifting or with poor thermal contact; uneven converter cooling making sensors A and B disagree.

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.