Cummins Fault Code 235

03/11/2025

Overview

CODE

REASON

EFFECT

Fault Code: 235
PID: P111
SPN: 111
FMI: 1/1
LAMP: Red
SRT:

The engine coolant is severely low.

Progressive power and/or speed derate increasing in severity from time of alert. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamp starts flashing.

Cummins Fault Code 235 — Engine Coolant Level Sensor Circuit

Circuit Description

The coolant level sensor is a switch and is used to measure the level of the engine coolant in the radiator top tank. The coolant level sensor is immersed in the coolant and returns a different signal voltage when immersed in coolant versus being out of coolant. The engine control module (ECM) monitors the change in the signal voltage to determine the level of the engine coolant.

Component Location

The engine coolant level sensor is typically located in the radiator top tank or surge tank. Refer to the OEM service manual for the location.

Conditions for Running the Diagnostics

This diagnostic runs continuously when the engine is running.

Conditions for Setting the Fault Codes

The Engine Control Module (ECM) detected the coolant level sensor signal voltage was greater than 3-VDC for more than 30 seconds, indicating severely low coolant level.

Action Taken When the Fault Code is Active

The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.

Exhaust gas recirculation (EGR) valve operation will be disabled.

Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.

The engine will be shut down if the Engine Protection Shutdown feature is enabled.

Conditions for Clearing the Fault Code

To validate the repair, start the engine and let it idle for up to 5 minutes.
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 ECM will turn off the red STOP ENGINE lamp 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.