2024 Hyundai Sonata: What to check before buying

The whole electrical system briefly cuts out while driving. Headlights, brake lights, the instrument cluster, the center screen and driver aids go dark for a few seconds, then reboot. It happens without warning, often at night and sometimes at highway speed. Some reports say the engine keeps running. Others say the car seems to shut off while still rolling. False seatbelt warnings can follow. Dealers often cannot reproduce it or find codes. Smaller reports cover a horn that stopped working at 16,000 miles and a speedometer reading up to 6 mph off.

Unwanted speed changes and rough shifting lead these reports. In one crash report, the car kept surging forward into a stopped vehicle while the driver pressed hard on the brake. In another, the car dropped from about 60 mph to 20 mph while passing, with no warning lights, three times. Other owners report hard jerks on cold start, and jerky acceleration and shifting that began after a dealer software update. A dealer confirmed a speedometer error, said it comes from the navigation system, and could not fix it.

Front and rear bumpers pop loose from their brackets. The gap shows most often along the top edge where the driver-side bumper meets the fender. Most gaps are small so far, about 1/8 inch, but one owner found both bumpers detached at roughly 1,500 miles and was told it was a known issue. Pushing the panel back in does not hold. Reports say the problem can return even after a dealer replaces the brackets. Separately, an under-engine splash shield left unfastened after dealer service tore off on the highway.

The speedometer comes and goes, reading about 5 mph off GPS and worse at higher speeds. The error tends to show up after a short stop and restart. One owner saw 26 mph on the display at a true 30. Dealers say they cannot reproduce it, and Hyundai has blamed signal delay in the Waze app. One report is more serious. At 75 mph the car slows itself and the dash shows a 20 MPH limit. Only a restart clears it, and it has happened several times.

Stability-control faults cause the car to veer toward highway medians and lose steering precision in turns and roundabouts. Near-collisions are reported at roughly 17,804 to 20,000 miles. The problem reportedly continued after the recall ESC software logic update (24-01-065H-1), and a later dealer visit found no fault. Both reports appear to come from the same owner, so the evidence is thin. Still, the described loss of steering control is a serious risk.

Automatic emergency braking can kick in during left turns and bring the car to a full stop, with the collision warning light on. In that report it started at just 60 miles and became a regular event. The other complaint concerns the Driver Attention Warning. It beeps about every 5 minutes during steady, attentive driving and can be set off by sunglasses. Unlike on earlier models, it cannot be turned off.

The low beams light too little of the road at night. Road signs and pedestrians stay poorly lit until the high beams come on. One owner noticed this at about 3500 miles on a Hybrid Limited. A second report covers the automatic high beams. When the camera by the rearview mirror is blocked, the high beams stay on all the time while the indicator still shows green. The driver may not realize the high beams are on.