If you are the owner of a car with the system INITIAL-D (or similar diagnostic protocols from Japanese manufacturers), then you know: dozens of undocumented commands are often hidden behind the factory settings. These combinations allow you to activate hidden multimedia functions, reset errors ECU, test sensors or even unlock additional engine operating modes. But without precise instructions, their use can lead to failures of the on-board computer or activation of unnecessary service modes.

In this guide we have collected all known INITIAL-D commands for cars Toyota, Subaru, Mitsubishi and other brands using similar diagnostic protocols. You will learn how to correctly enter codes through OBD-II or standard menu, what functions they activate, and where to find official documentation for your model. We will pay special attention commands that can lead to a system lock if used incorrectly — we will highlight them with warnings.

What is INITIAL-D and how does it work in a car

INITIAL-D (or Initial Diagnostic Mode) is a service diagnostic protocol developed by Japanese automakers for internal use by dealers and service centers. Unlike standard OBD-IIwhich provides a limited set of data, INITIAL-D allows:

  • 🔧 Activate hidden menus multimedia and climate control settings;
  • 📊 Read advanced parameters sensors (for example, oil temperature or turbine pressure);
  • ⚙️ Make changes into the firmware ECU without specialized equipment;
  • 🚨 Reset “eternal” errors that are not removed by a standard scanner.

The protocol works through OBD-II connector (usually using an adapter ELM327 or VAG-COM) or through the standard car menu (combinations of buttons on the panel). It is important to understand that not all commands are universal — their support depends on the model, year of manufacture and regional software. For example, the commands for Toyota Corolla 2018 may not work on Subaru Impreza 2020, even if both machines are equipped with INITIAL-D.

⚠️ Attention: Using INITIAL-D commands on vehicles with a valid warranty may void the warranty. Manufacturers consider this an interference with standard software.

Methods for entering INITIAL-D commands

There are three main methods for activating service commands:

  1. Via OBD-II adapter (for example, ELM327 or Launch CReader) using a terminal or specialized software like Torque Pro.
  2. Through the regular menu car (combinations of buttons on the control panel).
  3. Via diagnostic connector (for older models without OBD-II).

The most universal way is OBD-II. To do this:

  1. Connect the adapter to the connector (usually located under the steering wheel).
  2. Launch a terminal program (for example, Terminal Emulator for Android).
  3. Enter the command in the format: 
    AT SH 7E0

    21 01
    (where 21 01 - example of a command for requesting data).

Button combinations are often used to enter through the standard menu. For example, on some Toyota you need:

  1. Turn off the ignition.
  2. Press and hold the button Trip Reset (mileage reset).
  3. Turn on the ignition without releasing the button.
  4. The service menu will appear on the on-board computer screen.
📊 How do you usually enter diagnostic commands?
Via OBD-II adapter
Through the regular menu
I use a specialized scanner
Never tried

Complete list of INITIAL-D commands by category

Below are the most common commands, grouped by functionality. Please note that not all of them are supported by your model — before use, check compatibility in the manual or on thematic forums.

Category Command (HEX) Description Supported Brands
Diagnosis of errors 03 Querying Active Trouble Codes (DTCs) Toyota, Subaru, Mitsubishi
Diagnosis of errors 04 Resetting error codes Toyota, Lexus, Scion
Real-time parameters 21 01 Coolant temperature All with INITIAL-D
Hidden settings FF 00 08 Activating the multimedia engineering menu Toyota (since 2015)
Actuator tests 2E 01 Checking the operation of cooling fans Subaru, Mitsubishi

To activate hidden media features (such as turning on CarPlay on non-certified devices) often use the command FF 00 0A. However, entering it may cause the system to crash if the firmware does not support this option.

What to do if the command doesn't work?

If the system does not respond after entering the command, check:

1. Compatibility of the command with your model (on the forums or in the documentation).

2. Correct connection of the OBD-II adapter (must support ISO 9141 or KWP2000 protocol).

3. No diagnostic blocking on the part of the manufacturer (on some new models the ECU must be “unlocked”).

Dangerous commands: what can go wrong

Some INITIAL-D commands are capable permanently change ECU settings or activate modes intended only for factory tests. For example:

  • 🔥 FF 00 0D — reset of gearbox adaptations (can lead to jerks when shifting).
  • ⚡ 2E F0 — forced inclusion of fans at maximum speed (risk of motor overheating during prolonged activation).
  • 🚗 FF 00 05 — activation of the ABS test mode (can block the wheels while driving).

It is especially dangerous to use commands related to sensor calibration (for example, 21 0A to reset throttle adaptations). Incorrect calibration can lead to:

  • Unstable idle speed;
  • Increased fuel consumption;
  • Sunbathing Check Engine.
⚠️ Attention: Group teams FF (engineering) on vehicles with the system Toyota Safety Sense may disable driving assistance (e.g. Pre-Collision System). Before use, check that critical safety features are not disabled.
💡

Before entering any command, make a backup of the current ECU settings using the program TechStream (for Toyota) or Subaru Select Monitor. This will allow you to restore factory settings in the event of a failure.

How to find commands for your car model

There is no universal list of INITIAL-D commands - each manufacturer adapts the protocol to its needs. To find the latest codes for your vehicle:

  1. Read the service manual (for example, Toyota TIS or Subaru STIS).
  2. Search on thematic forums:
  • Use Databases like OBD-II Command Database (available as Excel tables).

    • For cars Toyota/Lexus a useful resource is the program TechStream — it automatically determines supported commands for a specific model. For Subaru performs a similar function Subaru Select Monitor 4.

    If you haven't found the command for your machine, you can try brute force method (not recommended for beginners!). To do this:

    1. Connect to OBD-II via terminal.
    2. Enter the command AT SH 7E0 (to initialize the session).
    3. Send commands from a range one by one 21 00–21 FF, recording the system's response.

    Check the compatibility of the command with the model|Make a backup of the ECU settings|Prepare an adapter with support for KWP2000|Have error documentation (DTC) on hand|Do not conduct tests on the move (only when parked)-->

    Examples of practical application of commands

    Let's look at some real-world scenarios where INITIAL-D commands can be useful.

    Scenario 1: Check Engine Error Reset After Oxygen Sensor Replacement

    If after replacing the lambda probe the error P0130 is not reset by the standard scanner, you can use the command:

    AT SH 7E0

    04

    This will force clear the error memory in ECU. If the error appears again, the problem is not in the sensor, but in the wiring or firmware.

    Scenario 2: Activating the hidden climate control menu

    On some Toyota Camry (2018–2022) additional climate settings can be unlocked:

    1. Turn off the ignition.
    2. Hold down the buttons Auto and Recirculate.
    3. Turn on the ignition (without starting the engine).
    4. Release the buttons and a menu with fan parameters and temperature thresholds will appear on the screen.

      5. Scenario 3: Turbo test on Subaru WRX

      To check the operation of the turbocharger without dismantling, use the command:

      AT SH 7E0

      2E 03

      The system will activate a test mode, where the turbine will operate at maximum pressure for 10 seconds. Important: Perform the test only with a warm engine and with diagnostic equipment connected to monitor pressure.

      💡

      The commands for testing actuators (groups 2E and 2F) should only be used with a diagnostic scanner connected to monitor parameters in real time.

      Common mistakes and how to avoid them

      Even experienced car owners make mistakes when working with INITIAL-D. Here are the most common:

      • 🔌 Using an incompatible OBD-II adapter. INITIAL-D requires an adapter that supports ISO 9141 or KWP2000 (cheap ELM327 They often don’t work with AliExpress).
      • 📱 Enter commands on the go. Some commands (such as ABS tests) may lock the wheels or disable braking assistance.
      • 🔄 Terminating a session. If you turn off the ignition while a command is being executed (for example, FF 00 0D), the ECU may remain in an unstable state.

    To minimize risks:

    1. Always check the on-board voltage before entering commands (must be at least 12.4 V).
    2. Use uninterruptible power supply (for example, NOCO Boost) when working with firmware.
    3. Do not enter more 3 teams in a row without rebooting the ECU (turn off/on the ignition).
    ⚠️ Attention: On vehicles with the system Start-Stop (for example, Toyota Corolla Hybrid) INITIAL-D commands may conflict with automatic engine shutdown algorithms. Please disable this feature in settings before use.
    Can INITIAL-D commands be used on European or American cars?

    The INITIAL-D protocol was developed by Japanese manufacturers, but some commands may work on models released for other markets (for example, Toyota RAV4 for Europe). However most engineering functions (groups FF) are blocked in US/EU versions of the software. Before use, check compatibility on the forums of the owners of your model.

    What should I do if the Check Engine light comes on after entering the command?

    First try to reset the error with the standard command 04. If this doesn't help:

    1. Connect the diagnostic scanner and write down the error code.
    2. Check if the test mode of any sensor is activated (for example, 21 0A for the throttle valve).
    3. If the error is related to incorrect calibration, try to restore factory settings with the command FF 00 01 (does not work on all models).

    If the problem persists, contact the service to reflash the ECU.

    How do I know if my car supports INITIAL-D?

    There are several signs:

    • Availability OBD-II connector with protocol support ISO 9141 or KWP2000 (can be checked with a scanner).
    • Inscription "Initial-D" or "Diagnostic Mode" in the service manual.
    • Ability to enter a hidden menu through button combinations (for example, on Toyota - retention Trip Reset).

    For an accurate check, connect to OBD-II and send the command AT SH 7E0. If the system responds 7E8, protocol supported.

    Is it possible to increase engine power using INITIAL-D?

    No, INITIAL-D commands are not intended for chip tuning. They allow:

    • Read current parameters engine operation;
    • Activate test modes (for example, forced opening of the throttle valve);
    • Reset adaptation after repair.

    To increase power, the ECU must be flashed using specialized equipment (for example, Cobb Accessport or OpenECU).

    Where can I download the official documentation for INITIAL-D?

    Official guidelines are distributed by brand:

    • Toyota/Lexus: Documentation available at TechStream (Dealer subscription required).
    • Subaru: manuals Subaru Select Monitor (SSM) can be found on forums like Subaru Outback.
    • Mitsubishi: Information is scattered throughout service bulletins (search by model on EvolutionM).

    An alternative is databases of enthusiasts, for example, OBD-Codes.com.