Your AI agent can read your car's error codes, check its sensors and tell you what's wrong. All you need is a $15 plug-in adapter. No car nearby? Use a virtual one.
Works with Claude Code, Codex, OpenClaw, Hermes and any AI agent that can run a command.
Cars: any car since 1996 (US), 2001 (EU) or 2020 (India), with almost any OBD-II adapter
Motorsport: race cars, karts, project cars and Formula Student cars
More than cars: cranes, diggers, generators and trucks, in one chat
Car to car: your cars talk to each other and sort things out
car-use Cloud: give every car its own always-on AI brain (early access)
Check engine light? Ask your agent.
You: My check engine light came on this morning. What's wrong?
| The agent… | What it found |
|---|
reads the error code · dtcs() | P0420: the catalytic converter isn't working well |
checks when it happened · freeze_frame() | At 2,210 rpm and 72 km/h. The fuel mix was normal. |
watches both oxygen sensors · watch(o2) | The rear one copies the front one. On a healthy car it stays steady. |
Agent: Most likely a worn-out catalytic converter. Have a mechanic check for an exhaust leak before the rear sensor first. If there isn't one, the converter needs replacing.
Setup
Paste this into your agent:
Install car-use with `uv tool install car-use`, run `car-use skill` and follow it, then read https://github.com/october-dev/car-use/blob/main/onboarding.md and walk me through it.
Your agent installs car-use, learns how to use it, shows you a practice diagnosis on a virtual car, then helps you plug in your adapter. You do the plugging in and turning the key. The agent does the rest.
Use your car
- Plug an OBD-II adapter into the port under the dashboard and turn the ignition on.
- Tell car-use where the adapter is:
car-use config set device tcp://192.168.0.10:35000 # Wi-Fi adapter (join its Wi-Fi first)
car-use config set device "serial:///dev/cu.usbserial-XXXX?baud=38400" # USB adapter (needs car-use[serial])
car-use doctor # is everything connected? tells you the one fix if not
car-use dongle-doctor # what adapter did you actually buy? graded A to D
car-use dongle-doctor --report # anonymised JSON to share (WMI and model year, not the full VIN).
# Takes ten minutes with the ignition on and prints its JSON at the end;
# --soak-seconds 30 takes a quick sample instead
Longer notes for Wi-Fi, USB, Windows and Bluetooth, plus which adapters are worth buying: setup/.
Buying a used car?
car-use inspect --expect-vin <the-VIN-from-the-windshield> # red / amber / green scan
car-use inspect --sim cleared-codes --html scan.html # try it on a virtual car
car-use inspect --md scan.md # save the markdown too
This is an OBD scan, not a mechanical inspection: codes, self-checks, identity and charging voltage. It does not compare odometer readings across modules yet. The report includes the full VIN, so don't post it publicly.
No car? Use a virtual one.
Pretend cars with real problems to solve. Pick one and let your agent work out what's wrong:
uv tool install car-use
car-use --sim p0420 <<'PY'
print(dtcs())
print(watch(["o2_b1s1", "o2_b1s2"], seconds=10))
PY
| Car | What's wrong | Difficulty |
|---|
p0420 | Worn-out catalytic converter. The rear oxygen sensor copies the front one. | Medium |
p0171 | Air leak. Fuel correction is high at idle and normal when driving. | Medium |
p0300 | Engine misfire. Shaky idle, two cylinders acting up. | Hard |
cleared-codes | The seller cleared the codes. Looks clean, but the self-checks haven't finished. | Tricky |
dying-battery | Battery not charging. Voltage keeps dropping while the engine runs. | Easy |
healthy | Nothing wrong. Use it to see what normal looks like. | Easy |
ignition-off | The adapter has power but the car doesn't answer. | Easy |
kwp2000 | Older car on KWP2000, not CAN. Several codes, slow to wake. | Medium |
iso9141 | Older car on ISO 9141-2. One code. | Medium |
p0128 | Thermostat stuck open. Coolant stays low after a long idle. | Easy |
p0442 | Small evap leak. The car drives normally. | Easy |
dpf-regen | Diesel filter regenerating. Idle and fuel use are high. | Medium |
hybrid-12v | Hybrid with a weak 12 V battery. The engine is not running. | Easy |
cng-bifuel | CNG car. The usual sensors look like a petrol car. | Tricky |
obd-2b | 2025 scooter on OBD Stage II-B. Only a few sensors answer. | Easy |
healthy-ev | Illustrative EV profile, not a real model. Almost no engine data, and nothing is wrong. | Tricky |
two-ecu | Engine and transmission both answer. Codes stay with the ECU that sent them. | Medium |
Each virtual car can also pretend to be a different adapter: a genuine ELM327, a cheap clone, or an OBDLink. Run one as a Wi-Fi adapter with car-use sim p0171 --port 35000 and point any OBD app at it. You can write your own in ~/.car-use/scenarios/.
How agents use it
Your agent sends short Python scripts. The helpers are already loaded. An agent with no shell can use the MCP server instead.
car-use <<'PY'
print(car().describe()) # which car and adapter
print(vin_info()) # model year, maker
print(dtcs()) # error codes, explained
print(readiness()) # the car's self-checks, and how long since codes were cleared
print(read_many(["rpm", "coolant", "ltft1", "battery"]))
PY
This is the beginning of the README. Read the rest at the original. Read the full README ↗
