Coolant Leaking problems of the 2021 Hyundai Sonata

One problem related to coolant leaking has been reported for the 2021 Hyundai Sonata. The most recently reported issues are listed below. Please also check out the statistics and reliability analysis of the 2021 Hyundai Sonata based on all problems reported for the 2021 Sonata.

1 Coolant Leaking problem

Failure Date: 01/01/2026

Hyundai technical service bulletin 23-em-009h (ehrs coolant leak) - aka a faulty heat exchange that causes the coolant to leak into the exhaust and burn away. Resulting in a very hard to diagnose coolant disappearance. This should be a recall. They have literally already acknowledged a manufacturer defect with the service bulletin. The problem is that in most cases, it occurs out of the 60k or 100k warranty. The dealer seems to have discretion as to which of the mileage limits apply. One dealer in nc told me 60k and my local in SC told me 100k. My problem started at ~90k, but was just topped off on fluid and repaired as "normal evaporation". Now 12k later at 102k, they acknowledged the TSB but claimed I was out of warranty. With me being out of warranty, they claimed that Hyundai would not send them TSB parts and that I would need to replace the whole system with the normal skus around $3k.


Other Engine And Engine Cooling related problems of the 2021 Hyundai Sonata



Sonata Service Bulletins
Sonata Safety Recalls
Sonata Defect Investigations