Talk to your classic car. In plain English.
Plug a simple USB KKL cable into your Mac and your 1990s or early-2000s car’s OBD port. KLine Diag reads and clears fault codes, explains them, shows live engine and transmission data, and logs a drive to CSV.
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Read stored and intermittent codes from the engine and transmission, with a plain-English description, the matching OBD-II P-code, and the fault type. Clear them when the job’s done.
Measuring blocks for RPM, coolant, load, air mass, timing, lambda control, fluid temperature and more, with gauges and a live graph.
Pick the blocks you care about, hit record, and export a CSV to chase down that problem that only happens on the highway.
Works with an inexpensive FTDI-based USB KKL cable and the K-Line protocol (KW1281) that VW-group cars used before CAN, so you don’t need a Windows laptop or a dealer tool.
Optionally connect your car to an AI assistant over MCP so it can read the same codes and live data and help you diagnose. Off by default, read-only unless you allow clearing.
Everything stays on your Mac. No account, no ads, no analytics. Nothing leaves your computer unless you switch on the AI connection yourself.
Screenshots show the built-in demo mode, so you can try every screen before you buy a cable.
Plug in the KKL cable at the OBD port and a USB port on your Mac. Ignition on.
Open KLine Diag. It wakes each control module and reads its codes and live data. These older cars talk slowly, so the first read takes a little while.
Click a code to see what it means and the measuring blocks worth watching.
Fix it, then clear it, and log a test drive to confirm.
Built and tested on a 1998 Audi A4 2.8 (B5). Other K-Line VW-group cars from the same era should work. Tell us how yours does.