Cummins Fault Code 6595

05/12/2025

Overview

CODE

REASON

EFFECT

Fault Code: 6595
PID:
SPN: 190
FMI: 11/11
LAMP: None
SRT:

The engine control module has detected the primary and backup speed sensor signals have lost synchronization or are connected backwards.

Engine may be shut down.

Cummins Fault Code 6595 — Engine Crankshaft Speed/Postion and Camshaft Speed/Postion Sensor Circuits

Circuit Description

The crankshaft position and camshaft position sensors are Hall effect type sensors. The engine control module (ECM) provides a 5 volt supply to the position sensor and a return circuit. As the teeth on the crankshaft speed ring or the dimples in the back of the camshaft gear move past the position sensor, a signal is generated on the position sensor signal circuit. The ECM interprets this signal and converts it to an engine speed. A missing tooth on the crankshaft gear is used by the ECM to determine the position of the engine.

Component Location

The crankshaft position and camshaft position sensor location varies, depending on engine model.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the engine is running and during cranking.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) detected a loss of both engine speed/position signals.

Action Taken When the Fault Code is Active

For On-Board Diagnostics (OBD) engines, the ECM illuminates the Malfunction Indicator Lamp (MIL) immediately when the diagnostic runs and fails.

The engine may not start.

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.
For On-Board Diagnostics (OBD) engines, the ECM will extinguish the Malfunction Indicator Lamp (MIL) after three consecutive trips where 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.

Shop Talk

This fault code indicates the crankshaft position sensor and the camshaft position sensor have lost synchronization or the wiring harness connectors are reversed.

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