The Sonata is spacious and well-equipped value, but the Theta II engine family's failure risk is the single most important check.
Compiled & reviewed by the VehicleFaults Research Team · last reviewed July 2026
The most commonly reported faults on the 2015–2019 Hyundai Sonata are Theta II 2.0T/2.4L engine failure (bearing/knock) — subject to recalls and warranty extensions, Excessive oil consumption and Panoramic sunroof struggles to open, grinds, or gets stuck in the tilted position. Of the documented issues, 1 rated critical and 2 rated high · these are the ones worth inspecting first. Full inspection points, onset mileage and what to check are listed below.
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Build the inspection planBased on the documented faults on this page for the Hyundai Sonata.
Guidance only · reflects reported patterns, not a specific car's condition.
Which faults an average example has usually reached depends on its age. Pick a model year for the faults that matter on that build.
Theta II 2.0T/2.4L engine failure (bearing/knock) — subject to recalls and warranty extensions.
Excessive oil consumption.
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Build the inspection planInfotainment and sensor glitches.
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.
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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.
Faults are compiled from documented recalls, technical bulletins, owner reports and mechanic sources, then reviewed for accuracy. This is guidance only · not a substitute for a professional inspection.
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