If you’re trying to program a key for a 2025 Hyundai Sonata and both Autel IM608 and Advanced Diagnostics Smart Pro fail — you’re not alone.
Several technicians have reported communication errors or ECU lockouts during All Keys Lost (AKL) programming, even when the correct dealer PIN is already purchased.
This guide explains why it happens and how to fix it.
🚗 Vehicle Information
- Vehicle: 2025 Hyundai Sonata
- Situation: All Keys Lost
- Tools Used:
- Autel IM608
- Smart Pro
- PIN Code: Pre-purchased (dealer PIN)
❗ Problem Description
- Autel IM608 cannot communicate with the ECU
- Smart Pro shows unknown error
- Vehicle does not enter programming mode
- Communication drops or immobilizer access fails
Even with the correct PIN, the system refuses programming.
🔎 Root Cause: ECU Lockout Protection
The main reason is:
The vehicle’s ECU / Immobilizer is in a temporary security lockout mode.
Modern Hyundai models (2023–2026) have enhanced anti-theft logic. If incorrect attempts are made or communication is interrupted, the ECU can lock programming access for several hours.
✅ Solution 1: Wait for ECU Unlock (Recommended First Step)
- Leave the vehicle untouched for several hours (preferably 24 hours).
- Ensure the battery is fully charged (use a stable power supply).
- Do not attempt repeated programming attempts during lockout.
- After waiting, retry key programming.
⚠️ Low voltage can trigger or extend lockout status.
🔋 Solution 2: Battery Reset Method
Some technicians report success using this reset approach:
- Disconnect the vehicle battery.
- Short the positive and negative cables together (not the battery terminals).
- Reconnect battery.
- Wait at least 5 minutes.
- Do NOT plug diagnostic tool in immediately.
- Then retry programming.
This may restore ECU communication.
🧰 Solution 3: Use Autel via Diagnostic Menu
Instead of going directly through the IMMO application:
- Open Autel
- Go to Diagnostic
- Select Hyundai manually
- Attempt immobilizer access from diagnostic side
Some users report improved communication using this pathway.
🔥 Solution 4: Use OBDSTAR G3 (Most Reliable for 2025 Hyundai)
Several technicians confirmed:
- Autel IM608 failed
- Smart Pro failed
- OBDSTAR G3 successfully woke the ECU
- Key programmed normally using dealer PIN
Why OBDSTAR Works Better?
- Stronger Hyundai/Kia protocol coverage (newer CAN architecture)
- Reads most PIN codes automatically
- Better compatibility with 2024–2026 Hyundai security updates
For newer Hyundai & Kia models, OBDSTAR has become the go-to tool.
⚙️ Important Programming Tips for 2025 Hyundai
- Always maintain stable 12V power (use power supply)
- Avoid multiple failed attempts
- Confirm correct system type (Smart Key vs Standard)
- Check for gateway module lock
❓ FAQ
Why does Autel IM608 fail on 2025 Hyundai Sonata?
New Hyundai models may trigger ECU security lockout, blocking immobilizer communication temporarily.
How long does ECU lockout last?
Typically 4–24 hours depending on system state.
Does Smart Pro support 2025 Sonata?
Yes, but communication errors may occur due to updated security firmware.
Is OBDSTAR better for new Hyundai?
For 2024–2026 models, OBDSTAR currently shows better stability and PIN reading performance.
🎯 Recommended Tools for Hyundai Key Programming
If you frequently work on newer Hyundai/Kia vehicles, consider upgrading to a tool optimized for latest immobilizer systems.
👉 Explore professional key programming tools at obd2tool.com
👉 Contact us sales@obd2tool.com for compatibility confirmation before purchase