Why it matters
The check-engine light can mean anything from a loose fuel cap to a serious fault. Reading the code yourself tells you how urgent it is, saves the cost of a diagnosis, and helps you understand what the workshop is telling you.
Read every kind of code.
Odo reads stored codes that turned on the light, pending codes that haven’t yet, and permanent codes that stay until the car confirms the fix.
- Stored, pending and permanent trouble codes
- Check-engine light status
- Freeze frame: the conditions recorded when a code was stored
- Codes read automatically when you connect on CarPlay
Codes in plain language.
Common codes come with a plain-language description and advice on what to do next. For anything else, one tap looks the code up on the web.
- Plain-language descriptions for common generic codes
- What-to-do guidance for each
- One-tap web lookup
- Code history per vehicle: first seen, cleared and how often it came back
Clear codes and check readiness.
Clear stored and pending codes after a repair, then use readiness monitors to see whether the car has finished its self-tests, useful before an emissions inspection.
- Clear stored and pending codes, with confirmation
- Emissions readiness monitors with an overall verdict
- On-board monitor test results
- A diagnostic report PDF to share with your mechanic
How to set it up
- 1
Plug in your adapter
Fit a Bluetooth LE or Wi-Fi ELM327 adapter to the OBD2 port, usually under the dashboard.
- 2
Connect in Odo
Turn the ignition on, then connect from Odo’s OBD screen.
- 3
Read codes
Open the Codes tab and read all codes. Tap any code for its explanation.
Clearing a code turns off the light but doesn’t fix the fault, and resets readiness monitors until the car re-runs its tests.
Guides
- How to connect an OBD2 scanner to your iPhoneWhich adapter to buy, where the port is, and the exact steps to connect a Bluetooth LE or Wi-Fi OBD2 adapter to your iPhone in under a minute.
- OBD2 adapter connects but shows no data? How to fix itThe adapter connects, but the car says nothing. Here's every common cause, in the order to check them, and the fix for each.
- OBD2 on Apple CarPlay: live engine data on your car's screenPut live engine data on your car's own screen: what Odo shows on CarPlay, how to set it up once on your iPhone, and how to pick your gauges.
Questions about Check engine codes
Which OBD2 adapters work with Odo?
ELM327-compatible adapters that connect over Bluetooth LE (4.0 or newer) or Wi-Fi. Quality varies, so an adapter from an established seller is the safest choice. Full answer
How do I connect my OBD2 adapter?
Plug it into your car's OBD2 port, turn the ignition on, then open Garage → OBD II in Odo and start the scan. Full answer
My OBD2 adapter doesn't show up in the scan. What can I do?
Unplug the adapter, forget it in iOS Bluetooth settings, start the scan in Odo, then plug the adapter back in while the scan is running. Full answer
