Skip to content

Background

How it works

MultiAuto is a focused OBD-II scanner for iPhone. It connects to a Wi-Fi ELM327 adapter on the adapter's local network, reads standard engine diagnostics, and offers safe standard code clearing without vehicle coding or programming.

The port

Most US-market vehicles from model year 1996 onward have a trapezoid-shaped, 16-pin OBD-II port under the driver's side of the dashboard. Its exact location varies by vehicle.

OBD-II standardizes access to emissions-related engine information. It does not expose every computer or feature in a modern vehicle, which is why MultiAuto is deliberately narrower than a professional full-system scan tool.

The port can remain powered with the ignition off. See Safety for battery guidance.

Why you need a separate adapter

An iPhone cannot plug directly into the OBD-II port. A Wi-Fi ELM327 adapter sits between the phone and the vehicle: it plugs into the port, translates OBD-II commands, and exposes a local TCP endpoint over its own Wi-Fi network.

MultiAuto defaults to the Veepeak VP01 endpoint 192.168.0.10:35000. You can enter a custom host and port for another generic Wi-Fi ELM327 adapter. MultiAuto's diagnostics are free; the adapter is a separate third-party purchase, and we do not sell adapters or take a commission.

No Bluetooth support in this version

MultiAuto does not connect to Bluetooth LE or Bluetooth Classic adapters and never requests Bluetooth permission. See the adapter table before buying hardware.

What MultiAuto reads

MultiAuto's standard diagnostic surfaces include:

  • Standard live data: current readings your vehicle exposes, with unsupported values labeled honestly.
  • Trouble codes: stored, pending, and permanent emissions-related codes, with plain-English summaries for common codes. If a code requires a manufacturer-specific definition, the app says so instead of guessing.
  • Supporting diagnostics: freeze frame, emissions readiness, and VIN.

Built-in dashboards show current values. Session recording and CSV export are available with MultiAuto Pro or during a Pro Day.

Free diagnostics and Pro tools

Connecting an adapter, live data, code scanning and safe clearing, freeze frame, readiness, VIN, one vehicle profile, and the built-in dashboards are free. MultiAuto Pro adds unlimited vehicle profiles, the custom dashboard editor, session recording, and CSV export. Every free user also gets two Pro Days each month. See the full Free vs Pro breakdown.

What it does not read

  • No ABS, airbag/SRS, transmission, body, four-wheel-drive, or other manufacturer-specific modules.
  • No coding, adaptation, actuation, service resets, key programming, ECU flashing, or arbitrary vehicle commands. Standard emissions-related code clearing is the only vehicle-changing diagnostic action.
  • No AI diagnosis and no repair instructions.

Why two similar cars can report different values

MultiAuto requests standard live-data PIDs, but OBD-II does not require every vehicle to support every PID. If the car does not expose a requested value, MultiAuto labels it as unsupported instead of displaying a misleading zero.

What a trouble code actually means

A diagnostic trouble code such as P0171 identifies a condition the vehicle detected. It does not prove that one named part has failed. The same code can have several possible causes, so it is evidence for diagnosis rather than a repair instruction.

MultiAuto shows the stored code and, for common codes, a plain-English summary. Manufacturer-specific meanings cannot be derived honestly from the code number alone; when a definition is not available, the app keeps the raw code and says that a manufacturer-specific definition is required.

About clearing codes

Some scan tools can send Mode 04 to clear emissions-related trouble codes. Clearing does not repair the fault: it can erase useful diagnostic evidence, remove freeze-frame information, and reset emissions readiness monitors until the vehicle completes additional drive cycles.

Clear codes carefully

MultiAuto's guarded clear flow sends the standard emissions clearing command only after parked-state guidance and explicit confirmation. It does not repair the underlying fault.

What you need to get started

  1. An iPhone running iOS 26 or later. MultiAuto is not available for iPad.
  2. A vehicle with a compatible OBD-II port.
  3. A generic Wi-Fi ELM327 adapter. Join its network in iOS Settings, then connect from MultiAuto using the default or custom host and port.

You can also use demo mode without a car, adapter, network, or permission. Simulated readings are clearly badged “Demo.”