This diagnostic is used to identify the cause of a noisy 1-BOX™ Aftertreatment.

Check as follows:

1. Visually inspect the entire exhaust system for signs of leaks or damage. Is any damage found?
   1. Yes; repair as necessary.
   2. No;Go to step 2.
2. Inspect that the aftertreatment inlet heat shields are not broken loose and rattling. Is there a loose or damaged heat shield?
   1. Yes; repair the heat shield. If the inlet heat shield has tabs, refer to 11 TS-6 .
   2. No; Go to step 3.
3. Inspect the inboard and outboard Diesel Particulate Filter (DPF) covers and verify nothing is loose or rattling. Is there a loose DPF cover?
   1. Yes; repair the loose cover.
   2. No; Go to step 4.
4. Turn off engine after inspection.
5. Disconnect the aftertreatment inlet pipe and start the engine to verify the noise is coming from the aftertreatment. Did the noise go away once the aftertreatment inlet pipe was disconnected?
   1. Yes; reconnect the aftertreatment inlet pipe and Go to step 6.
   2. No; inspect other truck components to identify the noise.
6. Connect DiagnosticLink^® .
7. Start the engine and run a Parked Regen. Monitor Diesel Oxidation Catalyst (DOC) inlet pressure and engine speed during the regen.

NOTICE:

If DOC inlet pressure is 19.9 kPa (2.9 psi) or higher at any time during the parked regen, immediately stop the regen because turbocharger damage may occur and Go to step 18.

1. Review the last seven minutes of the parked regeneration log data. The illustration below identifies the last seven minutes of the parked regen.

1. Is the Selective Catalyst Reduction (SCR) inlet temperature lower than SCR outlet temperature by more than 38°C (68.4°F)?
   Example : SCR Outlet temp 587°C (1090°F) minus SCR Inlet Temp 398°C (749°F) = 116°C (241°F). The difference between inlet and outlet temperature is 116°C (241°F), which is greater than 20.2°C (68.4°F).

1. Yes; Go to step 10.
2. No; Go to step 11. for log file review.
1. Perform a low temperature Aftertreatment Device (ATD) check using DiagnosticLink to check for a drifted temperature sensor. Are the SCR inlet and SCR outlet temperatures within 25°C (45°F) during the last five minutes of this test?
   1. Yes; replace the DOC/SCR module. This indicates internal structural damage; see image below. The ATD checklist is NOT required since the ATD is the primary failed part.

1. No; replace the drifted SCR temperature sensor and Go to step 11.
1. Review the parked regen log file. Compare your DOC inlet pressure reading to the screen shots below (steps 12, 13, and 14) to identify a possible cause of the aftertreatment noise.
2. Is the DOC Inlet Pressure starting out high above 10 kPa (1.45 psi) and decreases during a parked regen?
   1. Yes; Go to step 15.
   2. No; Go to step 13.

1. Is the DOC inlet pressure starting above the pressure specified below and stays high?

1. Yes; Go to step 16.
2. No; Go to step 14.

1. When the DOC inlet pressure starts out low and stays low , below 3.1 kPa (.45 psi), the Aftertreatment System (ATS) is considered noisy. Replace the DOC/SCR module. This indicates internal structural damage; see image below. The ATD checklist is NOT required since the ATD is the primary failed part. Verify repair.

1. This indicates that the DPFs were plugged and the parked regen has cleared them. Verify the noise is gone and complete the ATD check list to possibly identify why the unit was plugged.
2. The DOC is considered plugged. Since the DOC inlet pressure stayed steady and there is still a noise, run the DOC Face Unplugging procedure in DiagnosticLink under Actions-Aftertreatment. After completing the service routine, verify the noise is gone. Go to step 17.
3. Review DDEC reports to find out if excessive engine idle time is the cause of the plugged DOC.
4. The DOCs are severely face plugged. After cleaning, verify the noise is gone and release the vehicle.