2021 Hyundai Sonata: Power Train complaints
Owner-reported issue (NHTSA complaints, not a recall)
Symptoms
NHTSA has 25 owner complaints for the 2021 Hyundai Sonata that list the power train component. Complaints are individual owner reports, not verified defects.
Examples:
- NHTSA complaint ODI #11767539 (filed 09/28/2026): “My 2021 hyundai sonata n line suffered a catastrophic, sudden total loss of drive power while operating at speed on a public roadway, creating an immediate crash hazard. the vehicle lost forward propulsion and the gear selector flashed a blinking 'r' when reverse was attempted. the vehicle was towed…”
- NHTSA complaint ODI #11764277 (filed 09/15/2026): “Transmission replaced twice and all of them continue to fail. several hyundai service centers are unable to determine the cause and are only able to update/relearn and replace whenever they are able to replicate the issue. the issue is that at a cold start, the car makes a popping sound, jerks and s…”
- NHTSA complaint ODI #11759867 (filed 08/26/2026): “Massive loss of coolant in closed loop cooling system heat soak. fail safe mode…”
Likely causes
These complaints do not establish a single root cause; read the examples above and get a diagnosis.
Fix, in plain English
No single fix is established by these reports. Check your VIN for open recalls at nhtsa.gov/recalls, ask a dealer about technical service bulletins (TSBs) or extended warranty coverage, then have the system diagnosed.
DIY difficulty: Pro
Diagnosis needs a scan tool; repair or replacement needs a lift, transmission jack and the manufacturer's fluid fill/relearn procedure. (Our assessment.)
Cost
No sourced cost range for this issue. Get a written quote after diagnosis.
Typical parts (search links, no affiliate codes)
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Sources
Page last updated .