This is a step-by-step guide on how to install your KTuner Connectivity Device on your 2025 Honda Civic Si, and how to flash your tune safely onto your ECU. This requires a laptop and an internet connection, so please keep that in mind prior to completing these steps. You must have a KTuner Connectivity Device in hand to complete this, otherwise you will not be able to tune your vehicle. If you do not have the KTuner software downloaded on your laptop, you will need to do so prior to beginning. This can be found at https://www.ktuner.com/downloads.
1. Order your KTuner v1.2 or v2 device with the 2025 KTuner Connectivity add on. If you already have a KTuner unit, and just need the add on, you can purchase the KTuner Connectivity Device here.
2. Grab your laptop and make sure Battery Saver is off. If it’s low on battery, please plug it in before you begin. Make sure you are connected to the internet.
3. Open the hood of your vehicle and ensure that it is secured properly with the hood prop.
4. Grab the KTuner Connectivity Device, and make sure the toggle switch is in the “off” position.
5. From here, please remove the clamps (circled in orange) CAREFULLY from your ECU. Be sure to lift straight up and take extra care to NOT bend the pins. Replace with the KTuner supplied ones, keeping the connections as straight as possible. Please note the orientation of these.
6. Use the alligator clips and connect them to the battery. The red wire should go to the positive (red) terminal, and the black wire should go to a ground point within reach. Please see the below photo for reference - we put the positive clip on the nut of the positive terminal (circled in red), and the ground clip on the ground point bolt (circled in green).
7. Connect your KTuner device to the OBDII port supplied on the wiring harness (circled in blue). The KTuner v1.2 can plug straight in, but the v2 will need the associated cable to plug in.
8. Flip the toggle switch to the “on” position, and connect the cable from the KTuner unit to your laptop.
9. Once connected, please follow your on screen prompts to lock the unit to the ECU. It will ask to store your factory tune onto your unit. Please press yes, and allow it to move forward. DO NOT DISCONNECT THE UNIT OR ALLOW YOUR LAPTOP TO GO INTO SLEEP MODE WHILE FLASHING THE TUNE.
10. When it is done, it will likely go to a blank screen. From here, you can click “File”, “New Tune”, select your vehicle, click “Next”, select your desired tune, and click “Next” again. It will take a moment, but then your base map will load on screen.
11. After the tune has loaded on the screen, you can click “Tuning” and “Upload Tune”. It will ask if you want to store on the unit or flash to the ECU. Click “Flash Directly to ECU”, and let it erase/reflash without disturbance.
12. Once complete, it will ask you to key vehicle On/Off. You can do this with the toggle switch.
13. From there, it will let you know that the flash has completed. Place the toggle switch in the “off” position, and repeat these steps in the reverse order to remove the connectivity device and restore the ECU connection.
14. When completed properly, you can turn the vehicle on, hook the KTuner unit to your OBDII port, and use as usual to monitor live data.
Important Notes:
- Take extra care to not damage the clips on the ECU connectors.
- When removing/installing ECU connectors, please keep them as straight as possible to avoid bending or damaging any pins.
- The KTuner Connectivity Device does not work with the Hondata FlashPro.
- 2025 Acura Integra 1.5T compatibility is expected, but not confirmed at this time.
- 2/3/25 Update: KTuner released 1.0.13.1, which allows for 2025 users to use the OBDII port as normal after the initial flash to the ECU via Connectivity Kit.
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