Remote tuning · EK1 · DIY guide
The complete EK1 tuning guide.
Everything you need to tune your Hyundai or Kia from home with an EK1 device — from setting up the tool to flashing your first file. The tune itself is ordered on the Cherry Tuned portal; this guide covers the hardware side end to end.
Before you begin
What you'll need.
Flashing your own ECU is straightforward, but it isn't zero-risk. A few basics make it smooth and safe.
If formatting a microSD card or installing PC software doesn't faze you, you'll be fine.
You're flashing the brains of your car. Not much nerve needed — but a little.
For connecting the EK1 to your computer to update firmware and software.
Strongly recommended. A battery dying mid-flash can brick an ECU — keep voltage stable.
The hardware
Pick your EK1.
All EK1 devices read, write and data-log. The difference is screens, live gauges, DCT support and which ECUs they can talk to.
The cost-effective workhorse. Flashes tunes and does high-speed data-logging — everything you need for the remote process. No live gauges and no DCT tuning.
Everything the Mini2+ does, plus a full-colour screen for standalone live gauges (a digital boost gauge, etc.) and pairing with the EK1 app (Android) — currently the only way to do DCT tunes.
The latest device. Required for the newest Bluelink Smartstream ECUs (CPEGD3.20.1) that use the CAN-FD bus — the Mini2+ and Pro can't talk to those. If you've got a current Bluelink car, this is the one.
Bench cables & legacy: Smartstream 1.0/1.5/1.6T cars need a CPEGD3 bench cable, and the facelift Sedan/Elantra and "Facelift 2" i30N hatch (SIM2K-250/260) need a SIM2K bench cable to read/write — flashing those over OBD can brick the ECU. The older EK1 Lite is being phased out; if you have one the process is similar, but PC connectivity and updates differ. Not sure what your car needs? Ask us first.
Step by step
How it works.
From an unopened EK1 to a freshly-flashed tune. Take your time on each step — especially the flash.
Create an account at ek1tool.com, then download and install the EK1TOOL PC software (Windows). Connect the EK1 by USB-C and follow the prompts to update firmware. If the software opens in Korean, switch the language to English in settings.
Most 2.0T and 3.3TT cars don't need a stock read. 1.6T Smartstream cars generally do, and we'll sometimes ask a 2.0T owner for one after a fuel-pump recall or an unusual software version. Reading also gives you a personal backup, though there's a database of original files on the EK1 site.
⚠ Use the right cable. On SIM2K-250/260 and CPEGD3 ECUs, read/write over OBD can brick the ECU — use the correct bench cable. When in doubt, confirm with us before connecting.
Tunes are ordered on the Cherry Tuned portal using credits — buy a ready-to-flash pre-written (OTS) tune, or submit a fully custom request for your car and mods. Register your device serial + VIN in the portal first; each file is built bound to your device. Full walkthrough in the portal user guide.
Each tune downloads as a ready-to-flash .ekr file. Pop the microSD into your computer, copy the file into the Maps folder, and safely eject before removing the card. (No conversion needed for files from our portal.)
Pre-flash checklist: connect a battery tender; on pre-2020 2.0T, 3.3TT and 1.6T cars unplug the radiator fan; turn all accessories off (HVAC, radio, lights); then don't touch anything until it's done. Connect to the car, ignition fully on (engine not running), go to ECU Write, select your .ekr, and wait for "Success".
On SIM2K-250/260, run Reset Adaptive Values after flashing (especially stock→tune or tuner→tuner). The first start may crank longer or idle slightly rough for a moment as the ECU adapts — that's normal. Then log a drive and request revisions in the portal until it's perfect.
If something goes wrong
Troubleshooting.
The most common hiccups and how to clear them. When in doubt, stop and message your tuner in the portal.
"Cannot find the file"
Usually a microSD issue. Note the folder structure, then reformat the card to FAT32 — or replace it with a good-quality card from a reputable brand. It can also mean the file was coded for the wrong setup (e.g. a CANBOOT format for a non-patched ECU); message your tuner to confirm the file formatting.
"Incorrect file size"
The file may be coded incorrectly, or you're trying to load something that isn't a .ekr. Double-check you've copied the right file and reach out to your tuner.
Flashed, but the car won't start
Don't panic. Load your backup if you took one. If not, download the original from the EK1 portal and convert it to .ekr. Some ECUs (e.g. SIM2K-250) can encode the .ekr as a RECOVERY file; on SIM2K models you can also try loading a patch file. Then notify your tuner.
Write fails before reaching 100%
Generally safe to retry if the EK1 lets you — it sometimes takes 2–3 goes. If it keeps failing, run a recovery and notify your tuner.
Write fails right at 100%
Usually means the file is corrupted (a checksum issue on save, or corruption during encoding). Attempt a recovery and notify your tuner so we can re-issue the file.
Ready to tune?
Get your EK1, order your tune on the portal, and we'll guide the rest. Not sure what your car needs? Just ask.