CM850 Electronic Control System – FAULT CODE 1678

  Printable Version

Overview

Circuit: Catalyst Tank Temperature Sensor SMALL | MEDIUM | LARGE

Circuit Description

The catalyst solution temperature sensor is used by the electronic control module (ECM) to monitor the temperature of the catalyst solution inside the catalyst tank. The ECM monitors the voltage on the signal pin and converts this to a temperature value.

Component Location

The catalyst solution temperature sensor is located in the catalyst tank. The tank is mounted by the OEM. For more information, contact the OEM service manual.

Shop Talk

The catalyst solution temperature sensor shares return wires in the engine harness with other sensors. An open return can cause multiple fault codes to be active.

Possible causes of this fault code include:

• Open return circuit in the harness, connectors, or sensor.
• Open signal circuit or shorted to a voltage source.

On-Board Diagnostics (OBD) Information (Euro 4 Certified Engines):

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• The ECM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. The MIL lamp and fault code can also be cleared using the INSITE™ service tool.
• The fault code will be cleared from memory after 40 consecutive drive cycles where the diagnostic runs and passes.

On-Board Diagnostics (OBD) Information (Euro 4 Stage 1+ Certified Engines):

• The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
• An engine torque derate will be activated after 50 hours of engine operation with the fault code active.
• The ECM turns OFF the malfunction indicator lamp (MIL) after 1 ignition cycle that the diagnostic runs and does not fail. The MIL lamp cannot be cleared using the INSITE™ service tool.
• The fault code will be cleared from memory after 400 days or 9600 hours of engine operation.

Refer to Troubleshooting Fault Code t05-1678