About

What Diesel Trouble Codes is, how each guide is researched and checked, and how we handle corrections.

Updated October 15, 2026

Diesel Trouble Codes publishes plain-English diagnostic guides for diesel engine fault codes. Each guide covers one code on one engine platform: what the code means, the likely causes in order, how to check each one, and when a job belongs with a professional.

We currently cover:

• Ford Power Stroke: 7.3L, 6.0L, 6.4L and 6.7L
• Dodge/Ram Cummins: 5.9L 24-valve (VP44), 5.9L common rail, and 6.7L (split by emissions era: 2007.5–2012 and 2013+)
• GM Duramax: LB7, LLY/LBZ/LMM and L5P
• Medium and heavy duty: International DT466E, Cummins ISX15 and Detroit DD15, using each maker’s own code format (Navistar DTC numbers, Cummins fault codes, and J1939 SPN/FMI)

Who runs this site

Diesel Trouble Codes is a sole proprietorship registered in Colorado, USA. Questions, corrections and business inquiries: [email protected] — see also the contact page.

How the site is paid for

Every guide is free to read, with no account needed. The site is supported by:

• Display ads, shown to visitors (see the privacy policy for cookies).
• Amazon affiliate links on some tool recommendations. As an Amazon Associate we earn from qualifying purchases, at no extra cost to you. Tools are recommended because they fit the diagnosis, not because of the commission.

We don’t sell parts or repairs, and no manufacturer or shop pays for placement.

How a guide is put together

Every guide goes through the same pipeline before it is published:

1. Platform facts first. Each engine has a fixed hardware profile — injection type, turbo type, emissions equipment, cold-start system, timing drive. A code is only written against the platform it actually applies to (for example, the 7.3L Power Stroke uses HEUI oil-fired injection and has no fuel rail, so rail-pressure codes are not part of that platform).
2. Research against the SAE J2012 / ISO 15031-6 code definitions, each platform’s fact sheet, and owner-reported failures from NHTSA’s complaint database.
3. Draft, then a separate verification pass that checks each claim in the draft against its cited source. Claims that cannot be supported are removed.
4. Review. Guides that clear the automated grounding and safety checks are published; the rest are held for manual technical review before they go live.
5. Sources are listed on every page.

Costs, test values and common mistakes

These three sections come from small reference tables we maintain by hand rather than from the guide’s draft text, so every figure on the site traces to one place:

• Rough cost and difficulty — typical US independent-shop parts ranges and labor hours for each repair, checked against published parts and repair prices. Dealers usually charge more, and prices vary by region.
• Specs and test values — only values stated by a published source we have read, and every row links to that source. If we can’t source a value for an engine, we leave it out rather than guess.
• Common mistake to avoid — a known diagnostic trap for that engine and repair, again with its source linked.

Each guide also links to NHTSA’s recall lookup, because recalls are tied to your truck’s VIN.

Corrections

If a guide is wrong, incomplete, or misleading, tell us. Reader reports go to a private review queue — they are not published on the site — and are used to correct and regenerate the affected guide. A code that draws repeated reports is re-reviewed from scratch.

Corrections and questions: [email protected]

What we don’t cover

• Emissions-system deletes or defeat devices.
• Step-by-step repair of safety-critical systems where a mistake could cause injury or damage — we describe how to diagnose those, not how to repair them. When a repair belongs with a qualified diesel technician, the guide says so.

Disclaimer

Diagnostic information only, provided as-is. Always follow the factory service manual and observe safe shop practice. See the full disclaimer.