P249C

P249C-EXCESSIVE TIME TO ENTER CLOSED LOOP SCR REDUCTANT INJECTION CONTROL

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

Theory of Operation

The engine after treatment system monitors the soot load in the after treatment DOC/DPF Catalyst. Under normal operating conditions the after treatment DOC/DPF Catalyst is self-cleaning, where soot is converted to ash. The soot load in the DOC/DPF Catalyst is estimated using the Exhaust Pressure Sensor and the calculated soot output of the engine. The Powertrain Control Module (PCM) will set this fault if it detects that the after treatment DOC/DPF Catalyst is plugged or that the differential pressure across the DOC/DPF Catalyst is above the calibrated moderately severe threshold limit. The PCM will illuminate the MIL lamp immediately when the diagnostic runs and fails. The driver will be notified via the vehicle's EVIC Message Center. The PCM will turn off the MIL lamp immediately after the soot load has dropped below the Moderately Severe Level Threshold.

- When Monitored:
The diagnostic runs when an active soot regeneration is requested, ambient air temperature is above a calibrated threshold, and engine speed and fueling are in the operating window where soot regeneration is allowed.

- Set Condition:
If the time duration after an active soot regeneration is requested exceeds a calibrated threshold and the DOC/DPF Catalyst inlet temperature has not reached the light off temperature threshold to begin closed loop control.





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

1. OTHER RELATED DTCs
1. Turn the ignition on.
2. With the scan tool, read DTCs.

Were there any fuel system or air handling sensor DTCs present?

Yes

- If this DTC is present along with any fuel system or air handling system sensor DTCs, repair those DTCs before proceeding.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 2

2. CHECK THE EXHAUST TEMPERATURE SENSORS
1. Turn the ignition off for 10 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 43°F of each other?

Yes

- Go To 3

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.

3. CHECK THE ENGINE PERFORMANCE
1. Perform the CHECKING ENGINE MISFIRE / RUNS ROUGH / PERFORMANCE TEST diagnostic procedure. Checking Engine Misfire / Runs Rough / Performance Test

Were any problems found?

Yes

- Perform the appropriate repair.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- If DTC P1451 is present, perform a scan tool initiated regeneration of the after treatment system. If DTC P1451 is not present, replace the DOC/DPF assembly.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.