Causes For Onebox/DPF Failures/ATD Checklist

A common failure now on all EPA10 DD15 is becoming a one box and DPF failures, these are costly items to repair. To repair these failures correctly you must determine root cause for failure, as these parts will never fail on their own. Find the primary failed part and repair prior to replacing a onebox or DPF’s to prevent repeat failure down the road.

  1. Verify the air filter is installed correctly. Measure the Air Inlet Restriction with a manual gauge under 100% load (do not use the gauge on the air filter assembly). Is the Air Inlet Restriction greater than 18 H2 O”? Repair as required over restriction level.
  2. Pressurize the intake track, including the Charge Air Cooler (CAC) and associated piping, inspecting for leaks. Was a leak found? Repair for any leaks.
  3. Inspect for excessive oil coming out of the turbocharger compressor. If any oil is present Replace Turbo.
  4. With engine OFF, visually inspect the Exhaust Gas Recirculation (EGR) linkage for damage or limited travel. Repair for EGR component Failure.
  5. Using DiagnosticLink® , sweep the Intake Throttle Valve (ITV). Is the ITV stuck or is there limited travel? If a seized valve is found, repair as necessary.
  6. Inspect for exhaust leaks before the Aftertreatment Device (ATD). Are any exhaust leaks found? Repair all exhaust leaks.
  7. Inspect for plugged delta P ports. Are the delta P ports plugged? Clean/replace delta p if found plugged.
  8. Compare Inlet Manifold Pressure (IMP) ______ kPa ______ (psi) and Barometric Pressure (BP) sensor ______ kPa ______ (psi). Are both sensor readings within 10.3 kPa (1.5 psi) of each other? Replace IMP if found readings out of spec.
  9. Get readings of ATD temperature sensors with the ignition ON (key ON, engine OFF). Note coolant temperature. The best way to determine if a sensor has drifted out of range is to check the system with a cooled ATD.
    • Coolant ______ °C (______ °F)
    • DOC in ______ °C (______ °F)
    • DOC out _____ °C (______ °F)
    • DPF out ______ °C (______ °F)
    • SCR in _______ °C (______ °F)
    • SCR out ______ °C (______ °F)
  10. Inspect the CAC Outlet Temperature/Inlet Manifold Pressure (combination) sensor connector for corrosion. Was corrosion found? Repair as required.
  11. ct the IMT sensor connector for corrosion. Was corrosion found? Repair as required.
  12. Perform Idle Speed Balance (ISB) test. Then Perform a Relative Cylinder Compression Test with DiagnosticLink. Look for any internal damage, then proceed according to findings.
  13. Remove DOC inlet pipe from ATD and perform three throttle snaps. There should be one puff of smoke (the size of a basketball) that quickly clears. Is there excessive smoke? If yes, Manually cut cylinders to try and identify an over-fueling injector.

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