Diesel Repair Blog — Page 8
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 85–96 of 119 articles
Emissions
How to Tell a Bad NOx Sensor From a Real SCR Efficiency Problem
Use live NOx ppm, DEF pressure, and SCR temps to separate a failed NOx sensor from a real SCR efficiency fault before you buy parts.
2026-07-22
Emissions
How to Test DEF Concentration With a Refractometer (Step-by-Step)
Step-by-step DEF refractometer testing for 32.5% urea—sampling, temperature correction, reading the scale, and what to do when results disagree with the truck.
2026-07-22
Emissions
Inlet vs Outlet NOx Sensors: Which One Fails First and Why
Learn why outlet NOx sensors fail more often than inlet sensors, how to test both with live data, and when replacement actually fixes SCR faults.
2026-07-22
Emissions
J1939 Codes for Owner-Operators: What Your Cheap Scanner Misses
Cheap scanners miss J1939 live data, FMI detail, freeze frame, and inducement status—see what owner-operators need before buying parts.
2026-07-22
Emissions
JPRO Workflow for Aftertreatment: Regen, Data, and Inducement Reset
A practical JPRO aftertreatment workflow: gather faults and live data, run regen the right way, verify SCR/DPF PIDs, and handle inducement reset without guesswork.
2026-07-22
Emissions
Losing Power on Grades: Aftertreatment Causes Before Turbo Panic
Losing power on grades? Check derate stage, DPF restriction, and SCR inducement before you condemn the turbo—tests, pressures, and temps that prove the cause.
2026-07-22
Emissions
Low Battery Voltage and Ghost Emissions Codes: A Hidden Trap
Low battery voltage creates ghost NOx, DEF, and SCR codes that waste parts money. Learn the voltage tests, pass/fail numbers, and diagnostic order that stops the trap.
2026-07-22
Emissions
NOx Sensor Replacement Cost vs Misdiagnosis Cost for Fleets
Compare NOx sensor parts cost to fleet downtime from wrong diagnoses. Learn tests that prove a sensor is bad before you replace it again.
2026-07-22
Emissions
No-Start After a Derate: What the ECM Is Blocking and Why
Truck won’t start after a derate? Learn what the ECM may be blocking, how to separate true no-starts from severe limp, and the tests that find the real cause.
2026-07-22
Emissions
Paccar MX Aftertreatment Issues: What Owner-Ops Should Watch
Owner-op guide to Paccar MX aftertreatment issues: DEF, DPF, NOx warning signs, first checks, and when to stop driving toward a derate.
2026-07-22
Emissions
Parked Regen Won’t Start: 12 Checks Before You Call a Shop
A driver-and-tech checklist for parked regen inhibitors — switches, soot/ash, temps, codes, and conditions that block regeneration.
2026-07-22
Emissions
Passive vs Active vs Forced Regen: Which One Your Truck Needs
Compare passive, active, and forced DPF regenerations so you know what the truck is doing and when a parked regen is the right move.
2026-07-22
Showing 85–96 of 119 articles