Exhaust AfterTreatment Diagnostics on diesel vehicles is becoming more and more frequent as these vehicles age. Whether it be a problem with the Exhaust Gas Recirculation System (EGR), the Diesel Particulate Filter, or the Selective Catalyst Reduction System, having a thorough knowledge and understanding of these systems is the key to being efficient and successful when troubleshooting and repairing these systems. Topics covered:
*Code P0401 (EGR Insufficient Flow) Diagnostics & Criteria: “Is It Really an EGR Problem?”
What other factors not related to EGR can cause this code to occur?
What are the enabling system criteria for this code to set?
What are the resolutions?
*Diesel Particulate Filter Regeneration, Diagnostics, and Load Status Info
What is the DPF used for?
What symptoms does it present when there is a problem?
How do I check to see if it is restricted?
What are mitigating factors that cause the DPF to become restricted?
What other peripheral damage can a restricted DPF cause?
*Selective Catalyst Reduction Diagnosis and Expected Pid Data Reference Values
What values should I obtain during a road test when one of these systems is operational?
When does it work?
What are the enabling criteria for operation?
How do I get out of “Limp-In” Mode?
*How Upstream Issues Cause Exhaust Aftertreatment Problems
What can cause repeated DPF Regeneration Events?
What can cause repeated Exhaust System Restrictions?