DIAGNOSTIC MANUAL
9.5. SYMPTOM 4 (HEAVY DUTY): SPN 3719 AND OTHER ACTIVE FAULT CODES
NOTE – Before beginning the following step-based diagnostics, perform all vehicle operational checks
page 80.
Step
Action
Decision
1
Using Electronic Service Tool (EST) with ServiceMaxx™
software, check Diagnostic Trouble Code (DTC) list for
active fault code(s) other than SPN 3719 (DPF soot load).
Are fault code(s) other than SPN 3719 active?
Yes: Repair other active fault code(s)
(See Electronic Control Systems
Diagnostics in Engine Diagnostic
Manual). After repairs are complete, go
to step 2.
No: Go to step 2
Step
Action
Decision
2
Do Onboard Filter Cleanliness Test (OBFCT) to clear SPN
3719 active fault code. Using Electronic Service Tool
(EST) with ServiceMaxx™ software, go to Sessions >
Performance and select the record snapshot icon from the
toolbar. Then go to Tests > KOER Aftertreatment Tests >
Onboard Filter Cleanliness Test.
Is SPN 3719 still active after OBFCT is complete?
Yes: Go to step 3
No: Go to step 7
Step
Action
Decision
3
Determine if Diesel Particulate Filter (DPF), Pre-Diesel
Oxidation Catalyst (PDOC), and Diesel Oxidation Catalyst
(DOC) are contaminated. Remove the DPF, PDOC, and
DOC (see Exhaust System Service Manual), and check for
signs of lube oil and coolant contamination.
NOTE – A black staining in the exhaust tailpipe can
occur on applications that experience high idle times.
This is normal and the DPF should NOT be replaced.
Are the DPF, PDOC, or DOC contaminated?
Yes: Go to step 4
No: Go to step 5
Step
Action
Decision
4
Determine if DPF, DOC, and PDOC are reusable see DPF
and DOC reuse guidelines page 159.
Based on DPF and DOC Re-Use Guidelines, are the DPF,
DOC, and PDOC reusable?
Yes: Go to step 6
No: Replace failed component(s). After
repairs are complete, go to step 6
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