Cummins Fault Code 6337

24/12/2025

Overview

CODE

REASON

EFFECT

Fault Code: 6337
PID:
SPN: 862
FMI: 4/4
LAMP: None
SRT:

Low signal voltage detected at the crankcase breather heater circuit.

None on performance.

Cummins Fault Code 6337 — Crankcase Breather Filter Heater Circuit

Circuit Description

The crankcase breather heater is used to keep the crankcase breather filter housing from freezing. The ECM supplies battery voltage to the breather heater when heating is commanded.

Component Location

The crankcase breather heater is mounted to the crankcase breather filter housing.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) detected the crankcase breather heater signal circuit was shorted to ground.

Action Taken When the Fault Code is Active

The ECM logs the fault code immediately when the diagnostic runs and fails.

The crankcase breather heater will be disabled.

Conditions for Clearing the Fault Code

To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
The fault code status displayed by the recommended Cummins electronic service tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
The “Reset All Faults” command in the recommended Cummins electronic service tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.