Claude Code read a 32-year-old Jeep's engine computer through a $3 Arduino, found why it kept failing smog, and the owner open-sourced the kit
Muhammad (zulali on X) has a 1994 Jeep Cherokee that predates OBD2, so normal scanners can't talk to it. In a video that passed 1.5 million views, he shows wiring a cheap Arduino Nano to the diagnostic plug with three wires and letting Claude (with help from Codex) work out the old protocol, log real drives and track down a fuel setting he says was behind the repeated smog failures. He has published the scanner as xj-scanner on GitHub: open it in Claude Code or Codex, say "Help me hook this up to my Jeep", and the agent walks you through wiring, reading fault codes and logging live engine data. In replies he says he left the computer's hidden factory controls alone for the smog test because changing them is legally questionable.
Why it matters
It shows a coding agent doing hands-on hardware detective work on undocumented, decades-old electronics for about $15 in parts, the kind of job that used to need a specialist or a dealer tool that no longer exists.
Who it's for
Owners of 1991 to 1995 Jeeps and Chryslers, car tinkerers and makers who want to see what an agent can do with real hardware.
How to try it
- Clone github.com/MZULALI/xj-scanner and run its DEMO mode first to check the laptop side with a simulated Jeep.
- Open the repo in Claude Code or Codex and say "Help me hook this up to my Jeep"; the agent follows the repo's AGENTS.md step by step.
- Measure every cavity of the diagnostic plug with a multimeter before connecting anything (the README warns one cavity carries 12 volts).
- With the key on, read fault codes and log a drive, then ask the agent to explain the log in plain words; take any real fix to a mechanic.
Plan & availability: Applies to: the free xj-scanner repo (GPLv3) on GitHub, built and tested on one 1994 Cherokee XJ 4.0L; other 1991 to 1995 Chrysler/Jeep OBD1 computers may be close. Parts cost about $15 (Nano clone, breadboard, wires, spade terminals, multimeter). Works with Claude Code, Codex or another coding agent. Use at your own risk, and don't modify emissions controls: tampering is illegal in many places. Based on the author's X post and repo, read on November 11, 2026.
Note: reported by users on X; we haven't independently confirmed it works in the current version.
Related
Source: @zulali on X ↗
Written by AgentStackList from the original post. Checked Nov 12, 2026. Features, plans and availability can change, so confirm on the source before you rely on it.
claude-codecodexarduinocar-diagnosticshardwareopen-source
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