11 Fault Code Myths Debunked – What Technicians Really Need to Know
Share
1. “If the truck runs fine, I can ignore fault codes.”
Fault codes are early warning signs—even if the engine seems okay. Ignoring them can lead to major failures later.
2. “Fault codes always indicate something is broken.”
Not true. A fault code often flags a parameter out of range or a temporary glitch, not a failed component .
3. “All trucks use the same fault codes.”
Fault code naming and meanings vary by OEM and model year. Always use a diagnostic tool matched to your truck for accurate interpretation.
4. “Diagnostic tools are too expensive.”
While there’s an upfront cost, a well-made tool like OTR Diagnostics pays you back by preventing unnecessary downtime and repairs.
5. “Clearing codes fixes the problem.”
Code clearing only removes the alert—it doesn’t fix the underlying issue. Always diagnose and repair first, then clear to confirm the fix.
6. “Cheaper tools work just as well.”
Budget scanners often miss OEM-level data or misinterpret codes. Investing in quality software-hardware pairs ensures accurate readings and reliable support .
7. “You can wait until scheduled maintenance to check codes.”
Faults should be addressed immediately. Waiting increases the chance of serious breakdowns or emissions system damage.
8. “Only professional mechanics can resolve fault codes.”
With the right tool and some training, owner-operators and in-house techs can diagnose and repair most faults—no dealer required .
9. “My ELD takes care of fault codes.”
ELDs monitor compliance, not diagnostics. They don’t provide SPN/FMI or P-code insights—use a dedicated tool for real truck health data.
10. “My mechanic says don’t reset fault codes.”
Resetting is fine—but only after repairs. Clearing codes before fixing causes can mask recurring issues.
11. “Why pay attention to fault codes if they don’t fix my truck?”
Fault codes are diagnostic clues—they don’t repair your truck, but they guide you to the exact problem, saving time and money .
Tools Required
Final Takeaway
Understanding and responding to fault codes correctly—with the right tool, clarity, and timing—keeps your truck running smoothly and avoids preventable failures.