Hyundai Ioniq 9 Long Range RWD Mk1

The ICCU is the most significant known weakness of the E-GMP platform. It manages the flow of energy between the high-voltage battery, the 12V system, and external chargers. When it fails, the 12V battery drains gradually (even while driving), leading to loss of drive power, inability to charge, or complete immobilization. Root causes include overvoltage transients during charging cycles and thermal stress over time. Between 2 and 10 percent of Hyundai/Kia E-GMP owners have experienced ICCU-related issues depending on model year. Hyundai has issued multiple recalls and extended ICCU warranty coverage in Germany to 15 years / 300,000 km for Ioniq 5 and 6 models built up to mid-2024. The Ioniq 9 uses an updated ICCU design with improved cooling, but reports of failures on 2025-2026 E-GMP vehicles (including the Ioniq 9) continue to appear on owner forums. Out-of-warranty ICCU replacement costs approximately 1,500 to 2,500 euro including labour. If the 12V battery was also stressed, add another 200-500 euro for replacement. Dealers report wait times of 1-2 months for replacement units during peak demand.

E-GMP vehicles have a relatively high parasitic drain on the 12V battery. If the car sits parked for 5 to 14 days without driving or plugging in, the 12V battery can deplete to the point where the car will not start or shift out of park. This is a known platform characteristic rather than a defect in the traditional sense. The ICCU is supposed to periodically top up the 12V battery from the main pack, but if ICCU management is suboptimal or a software glitch occurs, it may not do so. The fix is straightforward: keep the car plugged in when parked for extended periods. Replacement of the 12V battery costs approximately 200 to 300 euro. Multiple owners report needing to replace the 12V battery within the first 2 years due to deep discharge damage.

One Ioniq 9 owner reported complete infotainment failure after 1.5 days of ownership, with the car in the shop for 5 weeks awaiting parts. Across the E-GMP platform, screen blackouts, touchscreen unresponsiveness, and failed software updates are recurring complaints. A soft reset (holding the power button) often restores function temporarily. If the head unit hardware fails, dealer replacement costs 2,500 to 3,500 euro. This is typically covered under warranty on new cars, but for used buyers outside the 5-year warranty, it can be an expensive repair. Software updates via OTA have improved stability on later production units.

The Ioniq 9's driver attention warning system uses an infrared camera to track the driver's eyes. Many owners report false inattention warnings, particularly when wearing glasses or sunglasses. The IR sensor can lose tracking when sunlight creates glare on lens surfaces. In extreme cases, the system has triggered emergency braking or deactivated Highway Driving Assist mid-drive. Hyundai has partially addressed this through software updates, but the issue persists for some drivers. The system can be disabled in settings, though doing so removes a safety feature. No repair cost unless a sensor itself fails (rare), in which case recalibration or sensor replacement runs 150 to 300 euro.

Hyundai recalled certain 2025-2026 Ioniq 5 and 2026 Ioniq 9 vehicles because the battery system may contain an improperly tightened bus bar, caused by rework errors at the battery supplier Mobis North America Electrified. The issue affects a small number of vehicles (27 units in the initial US recall). Dealers inspect and tighten the bus bar retention bolts or replace the battery assembly free of charge. This is a manufacturing quality control issue rather than a design flaw, affecting a very small production batch. Verify with Hyundai using VIN whether the car is affected.

Hyundai recalled certain 2025-2026 Ioniq 5 and Ioniq 9 vehicles produced between December 2024 and July 2025 for potentially under-torqued rear suspension fasteners. Symptoms include abnormal noise and vibration from the rear axle. If bolts detach while driving, vehicle control could be compromised. The recall covers US-produced vehicles from the Georgia Metaplant. European-delivered cars (built in South Korea) may have different production processes. Dealers inspect and re-torque or replace rear suspension fasteners free of charge. Only 172 Ioniq 9 units were initially affected.

E-GMP vehicles operate at 800V, which requires voltage boosting when connected to 400V chargers. This conversion adds complexity. Owners report sessions that fail to initiate on certain charging networks, abrupt charge stops, or charge curves that drop faster than expected. The Ioniq 9 with its large 110.3 kWh battery is more sensitive to charger compatibility than smaller-battery models. Most issues are resolved by trying a different charger or performing a vehicle reset. Software updates have progressively improved charging compatibility, but occasional problems remain. No direct repair cost unless the on-board charger module fails, which is rare and covered under warranty.