Why is my check engine light on?

Read My Car reads the fault codes behind the check engine light with an ELM327 OBD2 adapter, straight from your browser.

Free · No account · Your car’s data stays on your device

What it does

There’s no app to install and no account. It’s free, works offline once opened, and your car’s data stays on your device.

  • Reads stored, pending and permanent fault codes from every responding control unit, with plain-language descriptions and how urgent they are.
  • Clears fault codes after a repair, then reads them again to check whether they came back.
  • Shows live data, such as engine speed and the other readings your car supports, and records it to a CSV file.
  • Shows the VIN, the protocol and emissions readiness: the self-tests that inspections reading OBD, such as the Dutch APK, check.
  • Includes two demo cars, so you can try everything without an adapter.

What you need

An ELM327 OBD2 adapter
Bluetooth Low Energy adapters with an ELM327 chip: Vgate iCar Pro BLE, vLinker MC+ (Bluetooth 4.0/BLE version), OBDLink CX, Veepeak BLE and similar BLE adapters. Older “Bluetooth 2.0” adapters and USB cables work from a computer.
Chrome or Edge
On Android or a computer. On iPhone and iPad, use the free Bluefy browser. USB and “Bluetooth 2.0” adapters need Chrome or Edge on a computer.
A car with OBD2
Petrol cars from 2001 and diesels from 2004 in the EU (EOBD), and all cars from 1996 in the US. Older European cars on the K-line work too.

Questions

What does the check engine light mean?

The engine computer found a fault, usually in something that affects emissions, and stored a fault code for it. Reading the code tells you where to look. If the light flashes, stop when it’s safe to do so.

Can I read OBD2 codes without installing an app?

Yes. Read My Car runs in the browser and talks to the adapter through Web Bluetooth or Web Serial. You can add it to your home screen to use it offline, but you don’t have to.

Does it work on iPhone?

Safari on iPhone and iPad can’t use Bluetooth. Open Read My Car in the free Bluefy browser and connect a Bluetooth Low Energy adapter.

Can it read ABS, airbag or other modules?

No. Generic OBD2 reaches the engine and often the gearbox. ABS, airbag, body and comfort modules need the manufacturer’s own protocol and tools.

Does clearing the codes fix the fault?

No. Clearing turns the light off until the car detects the fault again, and it resets the emissions self-tests. Repair the cause first, and drive normally for a few days before an emissions inspection (APK, MOT, TÜV, contrôle technique).

Is my data sent anywhere?

No. Fault codes, live data and the VIN are read and kept in your browser. There are no accounts, cookies, analytics or ads.

Is it free?

Yes. It’s free, with no account and no ads.