Recall letter on my 2019 Sonata 2.4, they flashed the knock sensor software and now I am paranoid

toyota tech, not hyundai, so this is the general version and your dealer gets the last word.

the knock sensor software is not a repair. it is a listener. a failing rod bearing makes a specific vibration before it lets go, and the update teaches the engine computer to watch the knock sensor signal for that pattern. when it hears it, it lights the check engine light, stores a code and drops the engine into a reduced power mode so you get to a shop instead of putting a rod through the block on the thruway. that is the whole feature. it does not make a worn bearing better and nobody at hyundai is claiming it does.

what tells you something useful before any of that is oil level. check it on a flat surface every thousand miles for a few months and write the number down. these engines generally start eating oil before the bearing noise shows up, and a dealer taking you seriously later depends on you having numbers rather than a feeling.

warranty coverage on a recall campaign follows the vehicle, not the person, but an extension that came out of a settlement can have its own terms. your dealer can read the whole history off the vin in about a minute, including whether the car already had the inspection done under the last owner.

fourteen years writing service tickets, so the paperwork half of this is my part of the forum.

recall letters go to the registered owner at the address the state has. if you bought the car used, if you moved, if the title took a while, the letter goes to a house you do not live in and nobody tells you. do not wait for mail. put your vin into the owners section at hyundaiusa.com and look it up yourself, and do it again every spring.

when the work is done, take the repair order home and keep it. not the invoice, the repair order with the campaign number and the technician's notes on it. the day you need to prove that an inspection happened and what it found, that piece of paper is the whole argument. i watched people lose that argument twice a month for fourteen years, always the same way.

a charge nurse i work with had a 2015 sonata that ate itself at 96,000, in the roundabout outside the hospital, going maybe fifteen miles an hour. hyundai did replace the engine. it took five weeks, three of those waiting on the long block, and the fight was about the rental, not the engine.

what got her through it was that she had oil change records from one shop for the whole time she owned it. the service manager told her straight that the consumption test goes differently when there is a stack of receipts on the counter.

reporting back. dealer in cheektowaga did the flash and the inspection on the 14th, in and out in two hours, no charge, and they gave me the repair order with the campaign number like tanya said. tech wrote that he scoped it and found nothing, which i will take.

i have been checking oil every thousand since the 2nd. three checks now and it has not moved off the top mark, 3,100 miles into this change. so either i got one of the good ones or the problem starts later than i think.

the part that still bothers me is that nothing about the car felt different before the letter and nothing feels different after. i am driving the same car i was driving in july with a different idea in my head about it.

the nissan version of your letter is the cvt extension and it played out the same way. a lot of people got the extended coverage, never knew, sold the car, and the second owner paid cash for a transmission that would have been free with a phone call.

keep checking the oil after you get bored with it. that is the part everybody quits at month three.