Will an OBD-II adapter that is not on the list work with an iPhone?

What does a Bluetooth Low Energy adapter need to work with WrenchTime?

Four things, and most adapters sold as compatible with iPhone have all of them. None of them is a brand: an adapter from a maker nobody has heard of works as well as a known one if it ticks these boxes.

• Bluetooth Low Energy the listing says BLE, Bluetooth 4.0 or later, or that it works with iPhone. An adapter that is Wi-Fi only, or classic Bluetooth for Android only, cannot be reached by an iPhone app. The one classic Bluetooth exception is the Apple-certified OBDLink MX+.
• The ELM327 command set the adapter answers AT commands and ends each answer with a > prompt, as nearly every OBD-II adapter and clone does. The very first thing WrenchTime sends is a short identification command, and an adapter that never sends a prompt back is not kept.
• A channel to write to and read from the adapter exposes a pair of Bluetooth characteristics, one the app writes commands to and one that notifies the answers. The common layouts (services FFF0, FFE0 and 18F0) are tried first, then the adapter's other services, so an unusual layout is found too.
• A name it advertises names containing OBD, ELM, Vgate, vLink, iCar, Veepeak, Carista, Konnwei, Kiwi, LeLink or Scan are listed first, as recognized adapters. Any other named device with a usable signal is listed below them and can be tried just the same.

What else makes an adapter a good one for trips?

Waking up by itself. An adapter that sleeps when the car is off and does not come back when the app connects records nothing on a trip that starts while it is asleep, so for automatic trip recording that matters as much as working at all. The Vgate iCar Pro line wakes by itself; the non-Pro Vgate iCar has to be switched on with its button. If the listing or the maker says nothing about it, the first few drives will tell you: a trip that has engine readings from the first minute means the adapter woke up on its own.

Why should I tell you about an adapter that is not on the list?

Because it helps everyone who comes after you. The tested list grows only from what someone actually saw on a car, and an adapter you report, working or not, is added to WrenchTime's adapter log and to these pages with its status. A report that it failed is just as useful: it can point to a fix in the app, or at least save the next driver the purchase. Write from Settings > Support > Help & Feedback in the app, which opens an email with the app version and device already filled in. These details make a report most useful:

• The adapter its exact name and model as printed on it or on the listing, and the name it showed in the scan.
• What happened whether the scan found it, whether it connected and showed live readings, and whether it woke by itself on the next drive.
• The car make, model and year, since some adapters behave differently on some makes.
• The diagnostic log switch it on in the feedback form if you are willing: its technical details record what the adapter answered, which is often enough to add it without another question.