P040B

P040B-EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR 1 CIRCUIT PERFORMANCE





For a complete wiring diagram Refer to Diagrams/Electrical.

Theory of Operation


The exhaust gas recirculation temperature sensor is a variable resistor sensor and is used to measure the temperature of the EGR gas flow after it exits the EGR cooler. The ECM supplies 5-volts to the exhaust gas recirculation temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature. The EGR temperature sensor has two rationality tests: Key-on and Dither. The Key-on test fails if the EGR temperature sensor value is different than the key on temperature estimate by more than a calibrated threshold. The Dither test fails if the EGR temperature sensor value does not change by more than a calibrated threshold, over a calibrated period of time. If this fault becomes active the ECM will light the MIL light immediately. During this time the EGR valve will be closed. The ECM turns off the MIL when the diagnostic runs and passes in 4 consecutive drive cycles.

- When Monitored:
Ignition on

- Set Condition:
The Key-on test fails if the EGR temperature sensor value is different than the key on temperature estimate by more than a calibrated threshold. The Dither test fails if the EGR temperature sensor value does not change by more than a calibrated threshold, over a calibrated period of time.







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


Diagnostic Test


1. P040B ACTIVE
Ignition on, engine not running.
With the scan tool, read DTCs.
Is P040B active?

Yes


- Replace EGR temperature sensor.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test


No


- Go To 2



2. EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR
Turn the ignition off.
Disconnect the EGR temperature sensor harness connector.

NOTE: Check connectors - Clean/repair as necessary.

Remove the temperature sensor and reconnect the wiring harness connector to the sensor.
Turn the Ignition on, engine off.
Monitor scan tool, while heating the sensor with an external heat source (DO NOT USE OPEN FLAME).
Does the reading from the sensor increase at least 2.78° C (5° F) on the scan tool?

Yes


- Refer to the INTERMITTENT CONDITION - DIESEL Symptom. Intermittent Condition


No


- Replace EGR temperature sensor.
- Perform POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test