C7 and C9 On-Highway Engines Caterpillar

Illustration 1	g01449927
Diagnostic trouble codes for excessive soot load

These codes do not indicate that the Diesel Particulate Filter (DPF) must be replaced. Engine operation must be kept to a minimum in order to minimize the amount of soot that is created. Follow the troubleshooting procedure in order to minimize the amount of engine operation.

The Engine Control Module (ECM) maintains an estimate of the soot load in the DPF. The estimate is based on the engine's operating conditions. If the ECM estimates that the soot load is excessive, the ECM activates the applicable code.

Troubleshooting Procedure

1. Perform this test step if you are troubleshooting a 3715-31 code. Otherwise, proceed to Test Step 2.

   Use the Caterpillar Electronic Technician (ET) to view the differential pressure across the DPF. If there are two filters, view the differential pressure across both of the filters. The differential pressure is indicated by the following parameters:

   • "Diesel Particulate Trap #1 Differential Pressure"

   • "Diesel Particulate Trap #2 Differential Pressure"

   You may need to create a new group in order to view these parameters.

   Start the engine. Increase the engine speed to 1400 rpm. Monitor the differential pressure for 30 seconds. Stop the engine.

   If the differential pressure exceeds 15.0 kPa (2.1 psi), replace the appropriate DPF. Use factory passwords in order to clear the 3715-31 code. Return the vehicle to service.

   If the differential pressure is less than 15.0 kPa (2.1 psi), do not replace the DPF. Use factory passwords in order to clear the 3715-31 code. Continue to the next test step.

2. If the vehicle is equipped with an ARD disable switch, verify that the switch is not disabling the Aftertreatment Regeneration Device (ARD). Refer to the vehicle's service manual in order to determine the proper operation of the switch.

3. Troubleshoot any diagnostic codes that relate to the following systems or conditions:
   • Fouled nozzle

   • Low boost

   • ARD

   • Clean Gas Induction System (CGI)

   Troubleshoot the systems in the order that is listed above if there are diagnostic codes for more than one of the systems.

4. Perform the "ARD Nozzle - Test".

   Refer to Troubleshooting, "ARD Nozzle - Test" for the correct procedure. Proceed to Test Step 5 after the nozzles have been checked.

5. Perform the "Engine Air System Verification Test".

   Refer to Troubleshooting, "Air System Verification Test" for information on the test, if necessary.

   Troubleshoot the test results if the test results are unacceptable. Then, proceed to Test Step 6.

   Proceed to Test Step 6 if the results of the "Engine Air System Verification Test" are acceptable.

6. Perform this Test Step if all of the following conditions are true:
   • The ARD disable switch was not disabling the ARD.

   • The nozzles are okay.

   • The results of the "Engine Air System Verification Test" are acceptable.

   Proceed to Test Step 8 if a problem has been discovered and the problem has been resolved.

   1. Remove the inlet section from the DPF. Inspect the inside of the inlet section and the front face of the DPF. Look for oil and for excessive soot.

      The presence of a small amount of soot is a normal condition. Contact your local technical communicator for Caterpillar on-highway truck engines if you suspect that the amount of soot is excessive. Continue with this procedure after you have received guidance from the technical communicator.

      If oil is found, inspect the outlet of the turbocharger. Contact your local technical communicator for Caterpillar on-highway truck engines if oil is found. Continue with this procedure after you have received guidance from the technical communicator. Clean the oil from the inside of the inlet section of the DPF and the front face of the DPF. Assemble the DPF. Use Cat ET to disable the ARD. Set the value of the "Data Link ARD Disable Status" configuration parameter to "Disabled" in order to disable the ARD. Run the engine at 1400 rpm for 15 minutes. Then, proceed to the next test step.

      If no oil is found, leave the inlet section disconnected from the DPF. Use Cat ET to disable the ARD. Set the value of the "Data Link ARD Disable Status" configuration parameter to "Disabled" in order to disable the ARD.

      Perform a manual cylinder cutout test. Manually cut out each cylinder while the exhaust is monitored. Look for the smoke to disappear as each cylinder is cut out. Replace any injectors that cause the engine to smoke and run rough when the cylinder is not cut out. Clean the inside of the inlet section of the DPF and the front face of the DPF. Assemble the DPF. Run the engine at 1400 rpm for 15 minutes.

      Set the value of the "Data Link ARD Disable Status" configuration parameter to "Not Disabled" in order to enable the ARD. Then, proceed to Test Step 7.

7. Use Cat ET to perform an "ARD Ignition Test". This test operates the ARD for approximately five minutes. Troubleshoot any diagnostic codes that occur during the test. Then, proceed to Test Step 8.

8. Do not perform an "ARD Override" regeneration. Start a stationary regeneration by selecting the following menus on Cat ET:
   • "Service"

   • "Service Procedures"

   • "Manual Diesel Particulate Filter Regeneration"

   Look for a 310 diagnostic code after the stationary regeneration is complete.

   Return the engine to service if there is a 310 diagnostic code at the end of the stationary regeneration.

   Perform the following procedure if a 310 diagnostic code is not activated at the end of the stationary regeneration:

   1. Increase the engine speed to 1400 rpm.

   2. Use Cat ET to determine the differential pressure across the DPF while the engine speed is 1400 rpm.

   3. Return the engine speed to idle.

      Replace the DPF if the differential pressure of the DPF is greater than 15.0 kPa (2.1 psi) during engine operation at 1400 rpm.