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Heated Seat Turns on and Back Off

22K views 18 replies 14 participants last post by  Pete MacDougall  
#1 ·
So I noticed a little issue with my 2020 Sonata Limited today. We got some unusual weather today (couple inches of snow and single digit temps). My roommates and I went out to get our grocery order. I had to brush snow off the car and got pretty chilled, so I turned on my heated seat. I come to find out that the light will turn on in the console for a couple seconds and turn back off. The heated seat won't come on at all, and it disables heating and cooling for my seat until the car is restarted. The passenger seat heating works fine as well as the ventilation, and my seat didn't affect its functionality.

I'm not gonna make a big deal about this because I'm a warm person in general, and I rarely use heat in my car. This type of weather is also very uncharacteristic of the area where I live. 2 days ago we had high 70's and I had the sunroof open and the A/C on, and we'll be back in the high 70's by Friday. So I don't really have a need for the heated seats, today was just a freakishly cold day.

My guess is a loose connector under the seat, and I've read similar things after a web search. Just wondering if anyone's experienced an issue like this on their Sonata or any car in general? I'm not going to take it to the dealership because I had a very unpleasant experience purchasing the car and will not return there other than to retrieve my license plate. So if it's something I can fix then I'll take a crack at it. If not, no big deal. I should also mention that all other HVAC functions work fine in the car including the ventilation for the driver's seat.
 
#2 ·
You can take it to any dealer, no need to take it to the one you got it from (unless they are the only one in the area). This could be something simple or complex. At any rate, it's electrical in nature and should be addressed. Get Hyundai to look at it and fix it.
 
#6 ·
I had the same problem. Dealer ordered a part and fixed it but I only had the car one day before it went to the dealership for the transmission (55 days ago) so I don’t know if the fix is permanent. I also don’t know what the part was as it’s not noted on paperwork.
 
#9 · (Edited)
2017-19 Sonatas have a built-in diagnostics routine that we invoke to check the ventilated seats' ECM, NTC thermisters, and seat wiring.
If someone has the 2020-23 factory manual, they should be able to look up the diagnostics routine for your model.
 
#11 · (Edited)
Anyone get a final answer on this? I'm having intermittent functioning of the heat/ac for the driver side seat only. Passenger seat seems to work 100%
2020 Kona Electric

Update:
Found a link for the online service manual:

And here's the relevant page for heated seats:

I managed after several tries to get it into diagnostic mode (I think?). No flashing codes, but the seat is functioning normally right now....

I'll report back when I try again during a failure.
 
#12 ·
Anyone get a final answer on this? I'm having intermittent functioning of the heat/ac for the driver side seat only. Passenger seat seems to work 100%
2020 Kona Electric

Update:
Found a link for the online service manual:

And here's the relevant page for heated seats:

I managed after several tries to get it into diagnostic mode (I think?). No flashing codes, but the seat is functioning normally right now....

I'll report back when I try again during a failure.
As stated above it's usually a faulty seat heater grid. There are basically "safeties" built into the controller that senses an incorrect amount of power being requested and thus turn off the power supply. My '20 SEL had this issue last winter. You turned the switch on and it would light up for about 30 seconds and go off, and obviously the seat never heated up. Took it to the dealer and they called me with a diagnosis the first day and had is repaired the next day, as they had to order the part in.
 
#13 · (Edited)
I'm having the same issue up in BC Canada where our Winters get extremely cold, but I'm a senior lady who really hates being Cold!
My switch on the drivers side flashes for a few seconds and then turns off with no heat, but it had worked fine for 6 years. I'm wondering if I used it too much because I'd use it even when it wasn't cold just to get heat on my sore back due to my very physical job.
Does anyone have the price for the Hyundai part or what it cost you to have your heat fixed at a dealer or other shop?
I ask just so I don't get taken advantage of, being an elderly lady and all, but also so I have a general idea of the cost, and understanding the difference in USD and CAD!?!
Thank you in advance!!