Diesel Repair Blog — Page 6
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 61–72 of 119 articles
Diagnostics
P0087 Code on a Diesel Truck: Fuel Rail Pressure Too Low Diagnosis
P0087 means measured fuel rail pressure fell below the ECM target—usually a clogged filter, weak lift pump, leaking injector, or failing high-pressure pump.
2026-07-26
Diagnostics
P0401 Code on a Diesel Truck: EGR Flow Insufficient Diagnosis and Fix
P0401 means the ECM measured less EGR flow than commanded, usually from a clogged EGR passage, stuck valve, or bad sensor—not a DPF or turbo fault.
2026-07-26
Transmission
Allison 1000 Transmission Fault Codes: What Each One Means and What to Check First
Most Allison 1000 fault codes trace to voltage, pressure sensors, or solenoids, not a worn transmission. Check fluid and connectors before authorizing a rebuild.
2026-07-25
Engine
6.7 Power Stroke CP4 Fuel Pump Failure: Symptoms, Diagnosis, and Prevention
A failing 6.7 Power Stroke CP4 pump shows up as hard starts, hesitation, or a P0087 code, then sheds metal that wrecks injectors. Catch it early and it's just a pump job.
2026-07-23
Emissions
Aftertreatment Maintenance Schedule That Prevents Most Derates
A practical DPF, DEF, SCR, and sensor maintenance schedule fleets use to stop most derates before inducement timers start.
2026-07-22
Emissions
Best Heavy-Duty Scan Tools for Small Fleets (Without Dealer Prices)
Compare practical heavy-duty scan tools for small fleets—JPRO, OEM software, ETHOS, and interfaces—so you diagnose emissions faults without full dealer pricing.
2026-07-22
Emissions
Can You Keep Driving With a DEF Light On? What Happens Next
What a DEF warning really means, how long you can usually keep rolling, and the mistakes that turn a warning into a 5 mph derate.
2026-07-22
Emissions
Check Engine Light On, Truck Runs Fine: When to Stop Ignoring It
Check engine light on but the truck feels fine? Learn which faults are safe to finish the shift, which start derate clocks, and when to stop driving.
2026-07-22
Emissions
Codes Return After Regen: Incomplete Burns, Sensors, or Wiring?
Codes back after regen? Learn how to separate incomplete burns, bad sensors, and wiring faults with live data, soot load checks, and pass/fail tests.
2026-07-22
Emissions
Cold-Weather DEF Failures: Heaters, Frozen Lines, and False Codes
Diagnose winter DEF heater faults, frozen lines, and false codes with voltage checks, temps, and OEM tests before you replace the tank.
2026-07-22
Emissions
Contaminated DEF: How Water and Wrong Fluid Destroy SCR Systems
See how water-cut DEF, diesel cross-contamination, and wrong fluids damage SCR dosing, catalysts, and sensors—plus the cleanup order that stops repeat failures.
2026-07-22
Emissions
Cummins INSITE Basics: The Screens That Matter for Aftertreatment
Learn which Cummins INSITE screens actually matter for DPF, SCR, and derate diagnosis—plus the live data, pressures, and temps that separate real faults from noise.
2026-07-22
Showing 61–72 of 119 articles