Funny, my daughter had a similar experience, the engine rebuild took a few month, but apparently due to supply chain issues, and the alternator was wired incorrectly and she had to replace it immediately after. She also had the check engine light on a when she picked it up, although I forgot what the issue was.Original mechanic ran a test and basically said the car wasn’t “breathing right” and the convertor was clogged and advised to take it to the Dealership bc that shouldn’t be happening on a 5 year old car.
He was hoping to save me some $ and that the Delaer would cover some (or all of the repair) despite being over the warranty for miles.
Problem was there was no check engine light on and I didn’t ask him to try and look for a root cause (if there was one).
The engine on my Elantra was rebuilt last year at 102,000K (9 years old). They covered it under an extended warranty due to all the engine issues but it was a horrific customer service experience and took 4 months. The alternator seized when it was sitting on their lot (had to fight with them to cover it) and the Oxygen sensor was busted when they told me the engine was repaired (and they refused to cover that). So I left the lot with a check engine lot on after 4 months (even though my check engine light never came on when my engine was knocking and I needed a new engine and drove it there).
Since last year my Elantra with the new engine needed 4 different repairs for various sensors (two times it was the O2 sensor) and turned into a giant money pit so I just sold that this weekend for $3.5K.
One slight difference was that the dealership, Circle Hyundai, was easy to deal with.