2017 Hyundai Elantra cooling system problems: thermostat not working properly

Thermostat Not Working Properly

2017 Hyundai Elantra

This problem may be covered under warranty. Ask your Hyundai dealer.


pretty bad
Typical Repair Cost:
No data
Average Mileage:
4,300 miles
Total Complaints:
2 complaints

Most Common Solutions:

  1. not sure (2 reports)
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2017 Hyundai Elantra cooling system problems

cooling system problem

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2017 Hyundai Elantra Owner Comments

problem #2

Jan 022018

Elantra SE

  • Automatic transmission
  • 7,500 miles


I let the car warm up for 5 minutes without the heat on in my garage. I then got on the highway. At this point the car was still not heating up properly. It was about 5-7 minutes on the highway.

I had the heat temp all the way turned up to the hottest point and the fan on setting 4 (high). The video shows driving an additional 3-6 miles on the highway with these settings when I eventually get off at the exit after 15 minutes on the highway going 70 mph. At this point (as it’s been doing all along, since trying to fix the issue) it dropped to around a 1/4 on the temp coolant gauge until I parked my car.

- wagnej33, Lomira, US

problem #1

Nov 022016

Elantra SE 2.0L I4

  • Automatic transmission
  • 1,100 miles

Basically the thermostat in the 2017 Elantra 2.0 cannot regulate the engine temperature if the heater is blowing hot air. It seems that with the increased heat dissipation, it 'cools' down the engine too fast resulting in a drastic drop in temperature in the engine. That can't be good. I have tested several models besides my own and they all suffer from this. Picture this... It's New England in the middle of January and it's -8F outside... you start the car (also to note that it's the noisiest engine when cold) and give it a good minute before venturing.... in about 5-10 minutes, the engine temp starts to rise (heater blower still off)... when it finally gets to middle of gauge (normal), I switch on the heater blower full force... within minutes, the engine temperature drops to C and the blower spits out tepid air. If you continue to have the blower running after that, it climbs and dips constantly but I'd say in about 50 miles, it might finally be hot again. It's been to the dealer three times for this... they have replaced 3 thermostats... they have disengaged the 'electronic' part of this (causes engine light) and still it has the problem... leads me to believe that it's NOT a computer/sensor issue, but rather a badly designed mechanical thermostat.

- mgmgrand, Montague, MA, US

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