Newshot With Claude and an Arduino Board, an Enthusiast Got a 1994 Cherokee to Pass California Emissions Testing
IT之家 November 14 news — on the 13th local time, according to foreign outlet Tom's Hardware, an American AI enthusiast, Mohammed Zuraili, relying on AI and simple electronic wiring, successfully got a 32-year-old 1994 Jeep Cherokee to pass California's emissions test.
The old car's engine computer has very limited functionality, but after Zuraili connected it to a laptop via an Arduino Nano board, he could not only read vehicle data but also gradually gained control over some parameters.
His published video documents the whole process of Zuraili solving the emissions problem: from repeated test failures, to successfully connecting to the engine computer and reading data, to adjusting the engine and fixing the excessive emissions issue. Throughout the process, Claude handled the guidance while Codex handled writing the code.
The Cherokee had previously failed California's emissions test several times because its nitrogen oxide emissions exceeded limits at certain speeds. Initially, the vehicle failed the 40km/h test. Zuraili then adjusted the oxygen ratio in the air-fuel mixture, but the situation unexpectedly worsened, failing both the 40km/h and 80km/h tests.
Zuraili admitted that he had previously been tuning blindly with almost no accurate data, and each retest for emissions cost nearly 100 USD (IT之家 note: roughly 668.5 yuan RMB at current exchange rates).
Fortunately, in 2026 there's AI to help — and besides AI, all that's needed is a 3 USD (roughly 20.1 yuan RMB at current exchange rates) microcontroller, with all electronic components together costing no more than 15 USD (roughly 100.3 yuan RMB at current exchange rates).
The first thing to solve was how to get a 32-year-old engine computer to communicate with a modern laptop. Claude identified that the Cherokee uses Chrysler's SCI serial communication bus, at a communication rate of about 7?800 baud, with electrical signal polarity opposite to a standard serial port. The Arduino Nano board can handle the signal inversion, letting the laptop read vehicle data. Zuraili put the board on a breadboard and connected a few wires, three of which went into the Cherokee's 6-pin diagnostic connector.
The first connection succeeded, though the system initially could only log coolant temperature and battery voltage and plot their curves. Zuraili wanted to obtain more engine data and also to directly adjust some parameters to fix the excessive emissions problem.
Because he mistakenly referenced data from other models, the system twice misjudged the engine's air-fuel mixture as too rich, concluding fuel injection was 22% too high. After that, Zuraili had Claude collect data during test drives, recording engine parameters and fault codes at 40km/h and 80km/h respectively, to find the cause of the problem.
Claude was also granted permission to control parameters such as fuel pressure. After obtaining seemingly reliable diagnostic results and solutions, Zuraili originally intended to flash the AI-modified program into the engine computer so the vehicle would pass all of California's emissions test items. But the Cherokee's engine computer was simply too old — several months older than the version that could be reflashed with firmware — and did not support such an operation at all.
So Zuraili instead had Codex write custom code to a nearby EEPROM storage chip and run it directly. Zuraili admitted: "Claude did most of the diagnostic work, and Codex handled almost all the memory work. I was only responsible for wiring and driving."
The whole process also required no help from a repair technician, let alone reliance on the Chrysler dealership's proprietary diagnostic equipment.
Zuraili also uploaded the project used to diagnose and solve the Cherokee's emissions problem to GitHub, naming it xj-scanner. The project uses the GPLv3 open-source license, and anyone can use it for free.
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