A 2018 Hyundai Sonata is now 8 years old, so an average example has covered around 108,000 miles. A late-run car · the most reliable part of the generation, but higher-mileage wear items are usually the deciding factor. Check the state safety inspection and service history alongside the documented faults below, which are sorted by whether a 2018 car has usually reached the mileage where they appear.
Compiled & reviewed by the VehicleFaults Research Team
The 2018 Hyundai Sonata is 8 years old, so an average example has covered roughly 108,000 miles. At that mileage 7 of the documented faults are already due, so check those first.
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Build the inspection planDocumented onset mileage is at or below the ~108k miles an average 2018 car has covered.
Theta II 2.0T/2.4L engine failure (bearing/knock) — subject to recalls and warranty extensions.
Excessive oil consumption.
Electric power steering faults.
Clicking noise from behind the fascia and incorrect cabin temperature.
Vehicle refuses to crank, harsh gear engagement, or blank dashboard gear indicator.
Clunking, popping, or spring-binding noises from the front end at low speeds.
Panoramic sunroof struggles to open, grinds, or gets stuck in the tilted position.
Age, electronics and build-related issues that are not mileage-driven.
Infotainment and sensor glitches.
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Build my inspection planYes — the Theta II engines have a well-documented failure history with recalls; verify the knock-sensor update and any engine replacement.
It offers strong value, but only with confirmed recall completion and clean oil-consumption history.
Hyundai added a knock-sensor detection system to catch bearing wear early — confirm it was installed.
The 1.6-litre turbocharged Eco variant uses a seven-speed dual-clutch transmission that is prone to low-speed shuddering and premature clutch wear. During a test drive, pay close attention to pulling away from a standstill. If the gearbox hesitates or judders violently, it likely requires a software update or a costly clutch pack replacement.
Yes, models fitted with the electronic parking brake can suffer from rear brake calliper binding or actuator failure, often resulting from moisture ingress or lack of use. Check the rear brake discs for excessive scoring or blueing, and ensure the brake engages and disengages smoothly without triggering a warning light.
The Sonata Hybrid is generally robust, but the high-voltage battery cooling fan can accumulate dust and fail, leading to overheating and reduced battery performance. Additionally, the hybrid power control unit has been known to log faults. Always ensure no hybrid warning messages appear on the instrument cluster during start-up.
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