J1939FaultCode

J1939 Fault Code Lookup is the offline diagnostic reference for commercial-vehicle technicians, fleet mechanics and field engineers. Decode SAE J1939 diagnostic trouble codes in seconds — no internet connection required. KEY FEATURES ■ SPN Search Look up Suspect Parameter Numbers by number or keyword. See full parameter definitions including unit, range and resolution. ■ FMI Reference 23 bundled FMI definitions (0–21 and 31). Uncovered identifiers are reported explicitly. ■ DTC Diagnosis Look up covered SPN + FMI combinations. The fault database has 61 SPNs, 23 FMIs and 57 brand mappings. FMI-based guidance is general reference, not manufacturer/model-specific diagnosis. ■ Equipment Fault Records Organize an equipment alias, date, multiple fault codes, notes and review status. Draft and preview for free; Pro saves, edits and exports text reports. Uncovered codes can be recorded without invented definitions. ■ Brand Fault Codes Cross-reference OEM codes from Cummins, Bosch, Weichai, Yuchai and common aftertreatment systems. ■ CAN Signal Database 2,900+ J1939 messages and 16,000+ signal definitions with start bit, length, scaling, offset, range and enum values — perfect for calibration and network troubleshooting. ■ Favorites & History Bookmark frequently used codes; your search history is saved automatically. ■ 100% Offline Every database is built into the app. Underground garage, remote job site, no signal — it just works. PRO UPGRADE (one-time purchase) • Removes all ads (banner + interstitial) • Unlimited signal database detail views (free tier: 3 per day) • Save/edit local equipment records and export multi-fault text reports One-time purchase. Saved records remain viewable, deletable and exportable after revocation. Existing basic lookups, favorites/history and single-code copying/sharing stay free. WHO IS IT FOR Truck, bus and heavy-equipment technicians, service engineers, fleet managers, automotive electronics and calibration engineers, vocational students. DISCLAIMER All information is provided for reference only. Always consult the OEM's official service documentation before performing repairs. Records stay on your device, with no account or cloud sync. Export before deleting the app. Lookups and records work offline; purchases, restores and ads need a network connection.