nx_obd_dtc.nx

nx_obd_dtc.nx -- OBD-II diagnostic-trouble-code decoder (the AUTOMOTIVE vehicle-obd capability). Decodes a 5-char DTC (e.g. "P0301") into its structure -- system / SAE-generic-vs-manufacturer / subsystem / fault -- then CLASSIFIES severity and routes it to the platform action rung (DIY vs pro). Operator (2026-06-23): "cars" -- the first-listed maintenance domain; the CIQ top-build vehicle-obd-diagnostics (beat FIXD). THE EXCEED (on-thesis): FIXD reads the code + shows a generic blurb. We decode the structure, classify severity by system+subsystem, and turn the cryptic code into a routed ACTION (monitor / fix-DIY / fix-pro) via nx_maint_action -- and the platform's INDEPENDENT physics (battery via electrical, oil/brakes via consumable, bearings via rotating, fluids via fluid-seal) is the trust layer that cross-checks the car's self-report. The OBD code is one ingest, not gospel. HONEST: the DTC STRUCTURE is the SAE J2012 standard (decoded exactly). The severity-by-subsystem mapping is a reasoned starter heuristic (real per-code severity varies; the full code DB is a data-layer follow-up #11). NEVER-BRICK (#26): decodes a string; no syscalls, no vehicle writes, no code clearing. Read-only by construction. genealogy_id: project-maintenance-platform-sclass-2026-06-23 (automotive / vehicle-obd) license_tier: ORIGINAL