CM850 Electronic Control System – FAULT CODE 1664

Catalyst Missing – Condition Exists.


Fault Code: 1664
SPN: 3050
FMI: 11/31
LAMP: Amber

Catalyst Missing — Condition Exists. The aftertreatment catalyst in the exhaust system is not present.

Catalyst solution injection into the aftertreatment system is disabled.

Circuit: Aftertreatment Control System

Circuit Description

The catalyst is monitored by inlet and outlet temperature sensors that are located in the aftertreatment system. The inlet temperature sensor is located before the catalyst and the outlet temperature sensor is located at the outlet of the catalyst system.

Component Location

The catalyst is located in the exhaust system. The location of the catalyst may vary depending on the OEM.

Shop Talk

This fault code becomes active when the inlet and outlet temperature sensors do not detect the presence of a catalyst in the aftertreatment system. This can be caused by tampering with the catalyst system, the catalyst has been removed from the vehicle, or a failed catalyst. The catalyst temperature sensors must be reading ambient temperature and the engine must be off for a period of eight hours before this diagnostic will run. If the catalyst temperature is above 100°F [38°C], or the catalyst temperature sensors have a difference of more than 10°F or 5.5°C the diagnostics will not run.

Possible causes of this fault include:

  • Incorrect calibration revision on INCAL CD
  • Tampering with catalyst system, removal of catalyst from vehicle, or failed catalyst.

On-Board Diagnostic (OBD) Information:

  • The ECM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that 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 the memory after 40 consecutive drive cycles when the diagnostic runs and passes.

Refer to Troubleshooting Fault Code t05-1664

Last Modified:  08-Jul-2010