J1939FaultCode vs TruckOBD

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.

TruckOBD turns your phone into a powerful AI diagnostic assistant for big rigs, pickups, cars, SUVs, vans, buses, RVs, and motorcycles. Enter any trouble code and let AI do the heavy lifting: plain-English explanations of what each code means, how serious it is, and how to fix it. FEATURES • Trouble code lookup — enter any DTC and get instant answers • AI code explanations — understand what a code means and what to do about it • Vehicle health reports — a full picture of your vehicle's condition • AI mechanic chat — ask questions and get answers tailored to your exact vehicle • Failure prediction — spot problems before they leave you stranded • Part photo ID — snap a photo of a part and find out what it is • Demo dashboard — explore a simulated live-data view of engine readings • Nearby help — find gas stations, repair shops, and restaurants around you Works with any vehicle type. Pick your make and model from a complete, up-to-date vehicle catalog. No account required. No ads. Your diagnostic data is processed securely and never sold.