My phone is not discovering my obdII code reader Bluetooth but it work when searching for another phone or headset, what could possibly go wrong?

I would contact the BT ODB code reader manufacturer's support team, explain your problem, and ask if they have a firmware update for that device.

If your BT works fine with differen BT devices, it shouldn't be an issue on your iphone.

Read also the code reader user manual, and follow the steps provided in these support guides:

Pair a third-party Bluetooth accessory with your iPhone, iPad, or iPod touch - Apple Support

or

If you can't connect a Bluetooth accessory to your iPhone, iPad, or iPod touch - Apple Support

Regards

Giulio

Things to check:

• First, make sure the OBD III scanner is compatible with iOS. A lot of them are not. This information should be in the manual or on the website.
• You will need an app that is compatible with your scanner; iOS does not have a native scanner interface. The manual should tell you how to get a compatible app.
• There are two ways a Bluetooth device can connect to an iPhone
  • Paired mode, like headphones: Put the device itself into pairing mode (the manual should explain how), then go to Settings/Bluetooth. The device should appear in the device list if it is compatible with iOS; just tap on it. You will typically have about 30 seconds to complete this step. If it doesn't pair contact the manufacturer.
  • LE mode: This does not require and cannot use pairing. Open the app. Turn on the scanner. The app should recognize it after a few seconds.

No I can't, because I don't know which of the hundred or so OBD scanners on the market you have. But either the manufacturer's website or the manual should tell you which one to get. It's probably an app released by the manufacturer.

You can also go to the App Store on your phone and search for your scanner by name; you should then see a list of compatible apps.

You're quite welcome.

Best of luck.

Giulio

What did the OBD manual say about connecting to an iPhone when you read it?

Giulio was suggesting that YOU read the manual, not that he would read it.