2019 Hyundai Elantra - Seems to soon

On 03/07/2020 on my way home from Brooklyn, NY check engine light came on at 5500 miles. Took it in on 03/13/2020 and they said it was a bad thermostat. Only reason I got it replaced is that it was covered under the powertrain warranty. Don’t see why a thermostat would go out prematurely

You are saying that you would not pay to replace a thermostat on a 3 year old vehicle and take a chace of it overheating and causing thousands of dollar damage .

Things do fail .


Stuff happens.

This was over a year and a half ago. Any problems since then?

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It’s premature but things fail prematurely all the time. That thermostat was manufactured by some company other than Hyundai and any production line item is expected to have a certain percentage of failures. Thermostats are no different.

The only thing that would concern me was the one week delay in getting it to the dealer. Many an engine has been barbecued because of a lowly thermostat and the failure of the car owner to stop immediately. Hopefully in this case it was a Fail Safe thermostat.

Short answer, manufacturing defect. That is why you get a warranty.


Right in the middle of the Covid lock-downs? It never rains but it pours, eh? Thermostats are moving parts and moving parts almost always fail eventually, especially when they are immersed in coolant, which can be very corrosive. I’ve had thermostats purchase new from the auto parts store that have already failed even before I install them. After that happened the first time and had to do the job over again, I always test them in a pot of hot water & thermometer on the stove to make sure they open and close correctly w/temperature. Make sure to replace your car’s coolant on the schedule the manufacturer recommends as well.

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Hopefully, the error code was for the engine being too cold. But we’ll never know. It looks like our OP is another one-and-done poster.

I would seem that way.