CM850 Electronic Control System – FAULT CODE 1667

Exhaust Gas Temperature 1 — Data Erratic, Intermittent, or Incorrect


Fault Code: 1667
SPN: 3241
FMI: 2
LAMP: Amber

Exhaust Gas Temperature 1 — Data Erratic, Intermittent, or Incorrect. The exhaust gas temperature #1 sensor is not changing with engine operating conditions.

Default temperature value used for exhaust gas temperature #1.

Circuit: Exhaust Gas Temperature 1

Circuit Description

The exhaust gas temperature #1 sensor is used by the electronic control module (ECM) to monitor the engine exhaust temperature entering the catalyst unit. The ECM monitors the voltage on the signal pin and converts this to a temperature value.

Component Location

The exhaust gas temperature #1 sensor is located in the aftertreatment system. It is located between the turbocharger outlet and the catalyst unit inlet in the exhaust system.

Shop Talk

This diagnostic runs when the exhaust gas temperature sensors are compared to other engine temperatures during engine operation. The engine coolant temperature must be above 140°F before the diagnostic will run. If the value of the exhaust gas temperature #1 does not match the engine operating conditions, this fault code is logged.

Possible causes of this fault code include:

  • Stuck in-range exhaust gas temperature #1 sensor
  • High resistance in the exhaust gas temperature #1 sensor signal or return lines.

On-Board Diagnostics (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 memory after 40 consecutive drive cycles where the diagnostic runs and passes.

Refer to Troubleshooting Fault Code t05-1667

Last Modified:  08-Jul-2010