Diesel Repair Blog — Page 7
Long-form field guides for heavy-duty trucks — written for drivers and shop techs who need practical answers. Looking for a specific code? Search the diesel fault code library.
Showing 73–84 of 119 articles
Emissions
Cummins X15 Aftertreatment: The Fault Patterns Shops See Most
The X15 aftertreatment fault patterns shops see most—NOx, DEF dosing, soot, and regen failures—with INSITE checks and pass/fail tests.
2026-07-22
Emissions
DEF Doser Valve Failures: Crystals, Leaks, and False Efficiency Codes
Spot DEF doser valve failures caused by crystals and leaks, and separate them from false SCR efficiency codes using dosing tests and live NOx data.
2026-07-22
Emissions
DEF Pump Pressure Faults: Lines, Filters, Freeze, or the Pump Itself
Diagnose DEF pump pressure faults the right way: separate frozen lines, plugged filters, leaks, and true pump failure with live data and OEM tests.
2026-07-22
Emissions
DPF vs DEF Problems: A Simple Decision Tree for Drivers
Use a simple driver decision tree to tell DPF soot/regen issues from DEF/SCR faults before you tow, clear codes, or authorize the wrong repair.
2026-07-22
Emissions
Derate Stages Explained: Warning → Power Cut → 5 MPH Limp Mode
Break down heavy-duty derate stages from early warnings to severe speed limits so drivers and shops know how much time they really have.
2026-07-22
Emissions
Detroit DD15 Derate Codes: Root-Cause Map for Drivers and Techs
Map DD15 derate codes to root causes—DEF, SCR, DPF, NOx, and voltage—with DDDL checks drivers and techs can use before limp mode.
2026-07-22
Emissions
Detroit DDDL Basics: Finding the Root Code Behind a Derate
Use Detroit DDDL the right way: separate root SPN/FMI faults from inducement result codes, read derate stage data, and stop replacing parts on guesses.
2026-07-22
Emissions
EGR Faults That Look Like DPF Problems (And How to Separate Them)
EGR faults can mimic DPF soot load, regen requests, and power loss. Learn the live-data tests that separate EGR from aftertreatment failures.
2026-07-22
Emissions
Fleet Playbook: Cut Repeat Derates With Code History and Mentoring
A fleet playbook to cut repeat derates using code history, freeze-frame trends, tech mentoring, and driver reporting standards that stick.
2026-07-22
Emissions
Fresh DEF Still Throws Quality Codes: The Real Causes Techs Miss
Fresh DEF did not clear quality codes? Find the missed causes—tank residue, layered fills, bad headers, wiring, heaters, and incomplete inducement resets.
2026-07-22
Emissions
How to Capture a Useful Fault Stack Before the Shop Clears Codes
How drivers and techs can capture a useful fault stack—SPNs, FMIs, freeze-frame, and counts—before anyone clears codes and erases the diagnosis.
2026-07-22
Emissions
How to Get Out of a 5 MPH DEF Derate Without Guessing Parts
A practical path out of a 5 mph DEF/SCR derate: capture the fault stack, prove the root cause, then reset inducement the right way.
2026-07-22
Showing 73–84 of 119 articles