About Professional Diesel Repair
Real technicians. Real shop experience. Technical content you can trust when a truck is down and every hour counts.
Who We Are
Professional Diesel Repair was founded to solve a problem every technician and fleet manager knows too well: finding accurate diesel diagnostic information online is harder than it should be. Search results are cluttered with generic articles, outdated forum posts, and content written by people who have never turned a wrench on a Cummins ISX or a Detroit DD15.
Our team consists of ASE-certified diesel technicians, former dealership service advisors, and fleet maintenance managers with a combined 60+ years of hands-on experience across heavy-duty on-highway, vocational, and light-duty diesel platforms. We have diagnosed everything from intermittent SPN 3251 derates on over-the-road tractors to chronic DPF regen failures in municipal refuse fleets.
Our Expertise
We specialize in the diagnostic and repair domains that matter most to diesel operators:
- Fault code diagnostics — SPN/FMI interpretation, symptom correlation, and step-by-step troubleshooting for Cummins, Detroit Diesel, PACCAR, Volvo, Mack, International, Caterpillar, Powerstroke, and Duramax platforms.
- Aftertreatment systems — DPF regeneration failures, SCR/DEF quality issues, NOx sensor diagnostics, and DOC/SCR catalyst troubleshooting.
- Fuel and air systems — High-pressure common rail diagnostics, injector coding, turbocharger failures, and intake/exhaust restriction analysis.
- Repair cost estimation — Parts and labor pricing based on 2026 market data from independent shops, dealership service departments, and fleet maintenance programs.
- Fleet maintenance planning — PM interval optimization, TCO analysis, and downtime reduction strategies.
Our Editorial Standards
Every piece of content on this site follows a rigorous editorial process designed to meet the highest standards of technical accuracy:
- Primary source verification — Diagnostic procedures are cross-referenced against current OEM service manuals, TSBs, and engineering bulletins before publication.
- Field validation — Repair steps and cost estimates are validated against real shop invoices and technician feedback from active service environments.
- Regular updates — Content is reviewed and updated when OEM specifications change, new TSBs are issued, or pricing shifts significantly.
- Transparency — We clearly distinguish between verified OEM procedures and shop-practice recommendations. When multiple valid approaches exist, we document them.
Experience You Can Verify
Our contributors hold current ASE certifications in Medium/Heavy Truck (T-series), Diesel Engine (L2), and Electrical/Electronic Systems (E-series). Several team members maintain active technician credentials and continue working in shop environments, which keeps our content grounded in current practice rather than outdated textbook knowledge.
We do not accept pay-to-play content placement. Our fault code database, repair guides, and interactive tools are free to use because we believe accurate technical information should be accessible to every technician and truck owner — not locked behind a paywall or buried in a forum thread from 2014.
How We Build Trust
Trust in technical content comes from consistency, accuracy, and accountability. Here is how we earn it:
- We cite OEM part numbers, torque specifications, and fluid capacities wherever applicable.
- Our cost estimates include parts, labor hours, and regional pricing variance — not single-number guesses.
- We maintain a public contact page and respond to technical corrections from working technicians.
- Our disclaimer clearly states the limits of informational content and the importance of following OEM procedures in your specific application.
Contact the Team
Have a technical correction, a fault code we should cover, or a question about our content? We welcome feedback from technicians and fleet managers. Visit our contact page to reach the editorial team directly.