Inspection

m2 mm 49.01.002

Model year 2007 and later diesel engines in vehicles domiciled in the U.S. or Canada are required to meet all EPA exhaust gas emission regulations effective per the applicable emission model year and are equipped with an emission aftertreatment system (ATS).

Vehicles domiciled outside of the U.S. and Canada may not have aftertreatment equipment, depending upon local statutory emissions guidelines.

Important: The aftertreatment device (ATD), which is part of the aftertreatment system (ATS), requires special attention during regularly scheduled maintenance inspections. No leaks are allowed anywhere in the system. If any discrepancies are discovered, refer to the engine manufacturer's service literature for repair instructions.

  1. Check for leakage at the clamp that attaches the exhaust pipe to the turbocharger exhaust outlet. If leakage exists, tighten the nut on the clamp to the required torque. If leakage persists, install a new clamp.
  2. Check the exhaust pipe, bellows, and each exhaust seal clamp for leakage, wear, cracks, or damage. Replace damaged components as needed. If leakage exists at a clamp, tighten the nuts to the required torque. If leakage persists, install a new exhaust seal clamp. Do not reuse seal clamps. Once a seal clamp is loosened or removed, it must be replaced.
  3. If present, check the condition of the insulation material around the exhaust pipe between the turbocharger and the ATD.
  4. Check the ATD mounting bands for tightness. Tighten to 30 lbf·ft (41 N·m) if needed. Do not overtighten.
  5. Check for leaks around the clamps that attach the ATD in the ATS, and around the clamps that retain the DPF in the ATD.
  6. Check all sensors attached to the ATS for leaks or damaged wires. No leaks are allowed. See Fig. , see Fig. or see Fig. for Detroit Diesel ATS sensor locations.
  7. Check the DPF exterior surface for dents or other damage. A dent over 3 inches (76 mm) in diameter and 1/4-inch (6-mm) deep could cause internal damage to the DPF, causing it to malfunction.

    Note: The sensor box (item 8) contains the SCR inlet and outlet NOx sensors, DPF outlet pressure sensor, and the DOC inlet pressure sensor.

    Fig. 1, One-Box ATS Sensor Locations

  8. Check the SCR catalyst for dents and other damage.
  9. Check for heat discoloration on the surface of the ATD. Heat discoloration may indicate internal damage; especially around the DPF.

    1. DEF Metering Unit

    2. DEF Nozzle

    3. SCR Outlet Temperature Sensor

    4. SCR Inlet Temperature Sensor

    5. DOC Inlet Temperature Sensor

    6. DOC Inlet Pressure Sensor

    7. DPF Inlet Temperature Sensor

    8. DPF Outlet Pressure Sensor

    9. DPF Outlet Temperature Sensor

    10. DPF Outlet NOx Sensor

    11. SCR Outlet NOx Sensor

    Fig. 2, 2V2 Two-Box ATS Sensor Locations

    1. DPF Inlet Temperature Sensor

    2. DOC Inlet Temperature Sensor

    3. DOC Inlet Pressure Sensor

    4. DPF Sensor Box

    5. DPF Outlet Pressure Sensor

    6. DPF Outlet Temperature Sensor

    7. DPF Outlet NOx Sensor

    8. SCR Inlet Temperature Sensor

    9. SCR Outlet Temperature Sensor

    10. SCR Sensor Box

    11. SCR Outlet NOx Sensor

    Fig. 3, 2HV Two-Box ATS Sensor Locations

    10. Note: Diesel exhaust fluid creeps, causing white crystals to form around the line fittings. The presence of crystals does not mean the system has a leak. Replacing fittings or troubleshooting components is not necessary unless there is a system failure or a fault code.

  10. Check the DEF tank, pump, metering unit, and lines for leaks. See General Information, Diesel Exhaust Fluid System, EPA10 and Newer of the Business Class® M2 Workshop Manual for repair procedures.
  11. Check any wires, lines, or hoses within 4 inches (10 cm) of the exhaust system for heat damage. Repair or reroute as needed.
Note:
Parent topic: EPA10 and Newer Exhaust System
Document Number: 0000119755
Manual Publication Date: 2024-05-23
Topic Publication Date: 2024-11-06