P040C

P040C-EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR 1 CIRCUIT LOW





For complete wiring diagrams 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 exhaust gas recirculation temperature value is used by the ECM for the engine protection system, and engine emissions control. This fault code is set active if the sensor signal voltage is above or below the normal operating range for the sensor and the ECM has commanded the EGR valve open. This fault code will not be set active if the ECM has commanded the EGR valve closed. 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:

When the key is on and battery voltage is above 10.4 volts.

- Set Condition:

The circuit voltage to the ECM is below a calibration threshold for a calibratable period of time.







Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.

Diagnostic Test


1. DTC ACTIVE

With the scan tool, read DTC's.

Is DTC P040C Active?

Yes

- Go To 2

No

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

2. EXHAUST GAS RECIRCULATION TEMPERATURE SENSOR





Turn the ignition off.

Disconnect the exhaust gas recirculation temperature sensor harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the (K935) EGR temperature signal circuit and the (K914) EGR temperature return circuit of the EGR temperature sensor.

Is the measured resistance between 200 ohms and 2.4M ohms?

Yes

- Go to 3

No

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

3. (K935) EGR TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND

Turn the ignition off.

Disconnect the ECM harness connector.


NOTE: Check connectors - Clean/repair as necessary.

Measure the resistance between the engine ground and the (K935) EGR temperature sensor signal circuit at the sensor harness connector.

Is the resistance more than 100 k ohms?

Yes

- Go to 4

No

- Repair the harness.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

4. (K935) EGR TEMPERATURE SENSOR SIGNAL CIRCUIT SHORTED TO OTHER CIRCUIT





Measure the resistance between the (K935) EGR temperature sensor signal circuit and all other circuits at the ECM harness connector.

Is the resistance more than 100 k ohms?

Yes

- Go To 5

No

- Repair/replace harness.
- Perform POWERTRAIN VERIFICATION TEST. Powertrain Verification Test

5. ECM

Reconnect the ECM harness connector.

Reconnect the exhaust gas recirculation temperature sensor harness connector.

Turn the ignition on.

While monitoring with the scan tool, disconnect the EGR temperature sensor harness connector.

Is DTC P040D Set?

Yes

- Refer to the INTERMITTENT CONDITION Diagnostic Procedure. Intermittent Condition

No

- Replace and program the Powertrain Control Module.