Hyundai Sonata 2020–2021 — technical service bulletin
Bulletin 21-01-051H · NHTSA communication 10199099 · issued Jun 22, 2021
Technical service bulletin
communication type
Engine and Engine Cooling
component
2020–2021
model years
2
vehicle entries
Official summary
This bulletin provides information related to an Electronic Control Module (ECM) software update which revises the OBD Air Fuel Ratio Imbalance (AFRI) monitor function frequency and cylinder imbalance diagnosis logic.
Vehicles covered
What a TSB means. Technical service bulletins are repair guidance manufacturers send to dealers — they are not recalls, and repairs are not automatically free (warranty extensions are an exception worth checking). The full document is available via NHTSA’s vehicle lookup.