About C15-OBD
A full vehicle diagnostics suite that runs on the phone already in your pocket.
What the app does
C15-OBD turns your phone into an affordable scan tool. Plug a low-cost ELM327-compatible Wi-Fi or Bluetooth adapter into your car's diagnostic port, connect, and the app streams live engine data in real time — RPM, coolant temperature, throttle position, fuel trims, sensor voltages and more. You can read and clear stored, pending and permanent trouble codes, run a basic scan across the emissions-related systems, or dig deeper by scanning individual control modules over the UDS (ISO 14229) protocol used by most manufacturers.
Beyond fault codes, the app covers everyday ownership: reset service lights, calibrate sensors and run manufacturer adaptations, record a drive with the dash cam, keep a history of every scan session, track scheduled maintenance by mileage, and export your data as a report you can email or keep for your records.
The AI Diagnostic feature goes further still. Enter a fault code along with your exact vehicle — make, model, year, engine size and engine code — and you get a plain-English explanation of the fault, its most likely causes ordered by commonality, the tools and parts you're likely to need, and detailed step-by-step repair instructions with reference values, torque figures and the pitfalls to avoid.
Who it's for
DIY mechanics working on their own driveway, car enthusiasts who want to see what their engine is actually doing, and small independent garages, mobile mechanics and traders who need a quick, reliable way to read and clear codes on any OBD-II vehicle. It's for anyone who wants to understand what a dashboard warning light really means before paying a dealer to tell them.
It works on any OBD-II-compliant petrol, diesel, hybrid or electric vehicle, including cars, vans, and light commercial vehicles — see the vehicle coverage pages for the makes and models we list.
Who builds it
C15-OBD is built and maintained by a small independent team of automotive enthusiasts and software developers based in the UK. We are not affiliated with, endorsed by, or connected to any vehicle manufacturer — the diagnostic data and repair guidance the app provides is independent, and where we reference manufacturer procedures it's for information only. The project is self-funded and supported by an optional subscription that unlocks the premium tools, and by affiliate links to the adapters, tools and parts we genuinely recommend.
Have a question, a bug to report, or a vehicle you'd like to see covered? Get in touch — feedback from people using the app in real workshops is what shapes the roadmap.
How it connects
Wi-Fi readers
Join the reader's own network and connect straight from the app.
Bluetooth readers
Pair a Bluetooth adapter directly in Chrome on Android or desktop.
C15-OBD works with standard OBD-II data on vehicles that support it. Manufacturer-specific systems and older or non-OBD-II vehicles may not be available. Never operate diagnostics while driving.