Can't connect? Start here.

This is the most common one by far, and it is almost always the hotspot. On your iPhone, open Settings, Personal Hotspot:

1. Turn ON "Allow Others to Join." This is the big one. The hotspot button in Control Center does not switch this on, and if it is off, your MasterLink cannot see your phone at all. More setups are fixed by this single toggle than everything else combined.
2. Turn ON "Maximize Compatibility." The MasterLink talks on 2.4 GHz and iPhones default to 5 GHz, so without this it cannot find your hotspot.
3. Stay on that Personal Hotspot screen the whole time you run setup. iPhone quietly shuts the hotspot off if you navigate away from it.

Then run Settings, MasterLink, Set up over Bluetooth again.

That means the unit paired with your phone but could not get out to the internet through your hotspot. Check, in order:

• Allow Others to Join and Maximize Compatibility, both ON (above).

• The hotspot password you typed at setup, exactly, character for character. One wrong letter and it will not join.

• Keep the phone within a few feet of the unit during setup.

• Give it the full two minutes on the first boot before deciding it is stuck.

If MasterLink-XXXX is not in the list:

• Make sure Bluetooth is on on your phone.

• Give the unit about two minutes after you power it on, then open Set up over Bluetooth again.

• Keep the phone close to the unit.

• Power the unit down for ten seconds, back up, and retry.

Almost always power. Use a steady 5V 2.5A source. A weak phone charger or a marginal car adapter causes random reboots and can stop it ever coming online. If you can, plug it into a known-good wall supply on the bench first to confirm the unit is healthy, then move to the car.

Good, the hard part is done. For the read itself:

• Make sure the cable is seated firmly all the way into the OBD2 port under the dash, and the ignition is at least in the on position.

• On an older BMW with the round 20 pin port under the hood, you need a fully pinned 20 pin to 16 pin OBD1 adapter, one where every pin is wired through. The cheap partial adapters do not carry the diagnostic lines, so the car will not respond no matter what else is right.

• A few engines are still being added. The M cars with the S54, the Z4M and the E46 M3, use a different computer that I have not fully mapped yet. If that is your car, email me, it is on my list and I would love your help capturing it.

Do I need a computer?

No. If I built your unit, setup is entirely on your phone. Only DIY builders touch a computer, and only once, to flash the card.

What is my licence key, and do I type it in?

On a unit I built for you, your licence is already tied to your account and fills in automatically at setup. If you built your own, your key is on the download page when you are signed in. Your MasterLink locks that licence to itself the first time it comes online. That is normal, and it is what keeps your unit yours.

It worked before, now it will not connect.

Turn on your Personal Hotspot with Allow Others to Join on, open The Analogue, and hit Connect. If it still will not, power cycle the unit and try again. If a firmware update was mid-flight last time, leave it powered and on your hotspot for a minute, then retry.

Does it update itself?

Yes. Whenever it is online on your hotspot, it quietly pulls new firmware in the background. New protocols, new cars, and deeper reads all arrive that way, at no cost, with nothing for you to do.