3000 - 3999: 3119

3119-EXHAUST GAS TEMPERATURE SENSOR UPSTREAM OF CATALYTIC CONVERTER - PERFORMANCE

Theory Of Operation
There are three exhaust gas temperature sensors in the system. The first is located upstream of the Catalytic Converter. The second is located in the Catalytic Converter. The third is located upstream of the Diesel Particulate Filter. These are used by the Engine Control Module to monitor the exhaust temperatures in the system.

- When Monitored:
With the engine running.

- Set Condition:
The Engine Control Module (ECM) detects an implausible signal from the Upstream Catalytic Converter Temperature Sensor.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Initial Inspection and Diagnostic Overview

1. DTC IS ACTIVE

NOTE: The engine must be off for at least 60 minutes prior to performing this test procedure.

1. Turn the ignition on, engine not running.
2. With the scan tool, compare the three exhaust temperature sensors.

NOTE: With the ignition on and engine not running the sensors should read within 10°C (50°F) of each other.

Does the Upstream Catalytic Converter Temperature Sensor read within 10°C of the others?

Yes

- Perform the INTERMITTENT DTC diagnostic procedure. Component Tests and General Diagnostics

No

- Go To 2

2. UPSTREAM CATALYTIC CONVERTER FILTER TEMPERATURE SENSOR





1. Using the table as a guide, measure the resistance of the Upstream Catalytic Converter Temperature Sensor.
Is the resitance reading within specifications?

Yes

- Replace the Engine Control Module.
- Perform the ECM Verification Test. Verification Tests

No

- Replace the Upstream Catalytic Converter Temperature Sensor.
- Perform the ECM Verification Test. Verification Tests