P2000

P2000-NOX ABSORBER EFFICIENCY BELOW THRESHOLD
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation

The engine after treatment system monitors the oxygen content in the diesel engine exhaust. The Powertrain Control Module (PCM) monitors the exhaust gases for oxygen content and varies the rich/lean fuel mixture of the intake air fuel mixture to adjust system. This diagnostic measures the oxygen storage capability of the Nitrates of Oxygen (NOx) Absorber Catalyst. The PCM will set the fault if it detects that the NOx Absorber performance is lower than expected. A mobile desoot should not be performed while investigating this fault. The PCM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The PCM will turn off the MIL lamp diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
This diagnostic will run during deNOx events.

- Set Condition:
The Powertrain Control Module (PCM) will set the fault if it detects that the NOx Absorber performance is lower than expected.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. OTHER DTCs
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

Are any other DTCs present?

Yes

- Repair all other DTCs first.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 2

2. MAF SENSOR
1. With the scan tool, read The Mass Air Flow sensor.

Does the Mass Air Flow sensor read 0 +/- 2 lb/min?

Yes

- Go To 3

No

- Replace the MAF Sensor.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK FOR AN OPEN CIRCUIT IN THE UPSTREAM O2 SENSOR




1. Turn the ignition off.
2. Disconnect the Upstream Oxygen Sensor harness connector.
3. Disconnect the Smart O2 Sensor Module from the After treatment Wiring Harness.

NOTE: Check connectors - Clean/repair as necessary.

4. Measure the resistance of all circuits between the O2 Sensor 1/1 harness connector and the Smart O2 Sensor Module harness connector.






Is the resistance less than 5.0 Ohms on all circuits?

Yes

- Go To 4

No

- Replace the After treatment Wiring Harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

4. CHECK FOR AN OPEN CIRCUIT IN THE DOWNSTREAM O2 SENSOR




1. Disconnect the Downstream Oxygen sensor harness connector.
2. Disconnect the Smart O2 Sensor Module from the After treatment Wiring Harness.

NOTE: Check connectors - Clean/repair as necessary.

3. Measure the resistance between all circuits in the O2 Sensor 1/2 harness connector and the Smart O2 Sensor Module harness connector.






Is the resistance less than 5.0 Ohms on all circuits?

Yes

- Go To 5

No

- Replace the After treatment Wiring Harness.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. OXYGEN SENSORS
1. Remove the Oxygen sensors and inspect for signs of soot.

Is there soot on the oxygen sensors?

Yes

- Using pressurized air, blow out the soot deposits by applying the pressurized air directly into the center hole of the sensors. Reinstall the sensors. Go To 6

No

- Reinstall the sensors. Go To 6

6. EGR SYSTEM LEAK
1. Look for visible signs (soot streaks) of an external EGR leak. Check the EGR Valve and EGR Cooler for signs of a leak.

Are there any EGR system leaks?

Yes

- Repair the leak.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. CHECK THE INTAKE AIR SYSTEM
1. Perform the INTAKE AIR SYSTEM PRESSURE TEST. Intake Air System Pressure Test

Are there any leaks in the system?

Yes

- Repair the leak.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 8

8. CHECK FOR EXHAUST LEAKS
1. Perform the CHECKING THE EXHAUST SYSTEM FOR LEAKS diagnostic procedure. Checking The Exhaust System For Leaks

Are there any leaks in the system?

Yes

- Repair the Exhaust system leaks.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Perform the AFTERTREATMENT INSPECTION GUIDELINE procedure. Initial Inspection and Diagnostic Overview