P21B4

P21B4-NOX ABSORBER - OVER TEMPERATURE

Special Tools:






For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the engine running, the NOx Absorber Catalyst (NAC) outlet temperature is valid and no Exhaust Temperature Sensor 3 DTCs present.

- Set Condition:
When the NAC outlet temperature exceeds a calibrated high threshold for a calibrated period of time.





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

1. CHECK THE EXHAUST TEMPERATURE SENSORS
1. Turn the ignition off for five minutes to allow the Exhaust Temperature Sensors to stabilize.
2. Turn the ignition on, engine not running.
3. With the scan tool check the temperature values of the Exhaust Temperature Sensors.

Are the Exhaust Temperature Sensors reading within 6°C (43°F) of each other?

Yes

- Go To 2

No

- Replace the Exhaust Temperature Sensor that is out of range as compared to the others.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

2. CHECK THE FUEL INJECTORS
1. Using Fuel Rail Cap to cap off Fuel Injectors one at a time to determine if a Fuel Injector is leaking into a cylinder.

Were any of the Fuel Injectors found to be leaking?

Yes

- Replace the faulty Fuel Injector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Replace the NOx Absorber Catalyst.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.