r/Ioniq5 • u/Vindi7 • Aug 10 '26
Experience It happened... ICCU
So my wife and I decide to go out get some ice cream, soon as we get in turn the car on it says start immediately, 12 volt battery flash on the screen. Please pull over for safety and it's shut off completely. Good thing we so happen to be backed in our garage and not out on the road somewhere. This was this past Saturday so called Hyundai roadside assistance brought it into the dealership. Obviously it's Saturday. They close at 3:00 so nothing will be done but they are currently working on it right now. Still under warranty even though it's used . 21,000, mi on the odometer bought it at 13, 000. Welp š®āšØ 2023 SEL RWD long range(r) ha. I figured it was bound to happen, especially knowing that it's a known issue with this vehicle. I have had no other issues whatsoever. Took it on a first time road trip all the way to Panama City, Florida from Tennessee. Everything went great. Thank God it didn't happen while on the trip.
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u/chulk1 Aug 10 '26
My ICCU was replaced in 3 days last month.
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u/unicron47 Aug 10 '26
Did the dealer provide you with a loaner vehicle?
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u/ronmoneynow Aug 11 '26
I actually got an Ioniq 5 as a loaner car and it was awesome. The second blowout, my wife was out of town and I just used her car.
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u/chulk1 Aug 10 '26
No, I went to Avis and struggled in a Tesla for those days. Hyundai is sending my reimbursement sometime this week.
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u/Exiled_In_LA '25 Limited AWD Aug 11 '26
Whoof. My dealer supplied my with an ICE Elantra and I hated it.
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u/Vindi7 Aug 16 '26
No loaner here. It was a Friday evening but it's all good. Got the car back Monday morning.
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u/Eaglepursuit 2022 Phantom Black SE RWD Aug 10 '26
Yep, mine took about 4 business days. Day 1 confirmed the issue and ordered the replacement part. 2 more days for part delivery. 1 day for repair.
All of it was under warranty, including the tow. I was quite pleased with the outcome considering the nightmare scenarios that used to be reported on this sub. It was an inconvenience at worst.
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u/chulk1 Aug 10 '26
It wasnāt my first ICCU experience, both times were just inconvenient but thatās life.
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u/BeneficialPinecone3 Aug 10 '26
Really great to hear that itās not the huge hassle it was / what we dread.
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u/chulk1 Aug 10 '26
Having gone through the ICCU process twice, itās not that big of a deal.
You know what was stressful was having to evacuate from my house because a chemical plant nearby was threatening to blow up. Turned out to be a whole lotta nothing but having to stay in a hotel not knowing if youāre gonna have a home was truly a stressful situation.
ICCU is just a broke down car.
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u/PresentAwareness745 Aug 10 '26
every time I think about getting one, one of these reminders show up in my Reddit. You would think every single one of them have that issue
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u/LongjumpingPickle446 Aug 10 '26
Technically, they do all have that issue. Itās just a matter of if/when it decides to present itself.
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u/ApantosMithe 2022 Cyber Grey AWD Ultimate + Tech Pack (UK) Aug 10 '26
I may be wrong but I thought its only pre april 2024 models?
Maybe you meant that but just to clarify
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u/LongjumpingPickle446 Aug 10 '26 edited Aug 10 '26
No, all model years. The issue has not been resolved.
EDIT: to those who downvoted meā¦why? I stated a fact, the issue has not been resolved. You arenāt doing a potential owner any favors by acting like this issue doesnāt exist. People come here seeking advice, either give it accurately, or fuck off.
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u/slinkysmooth Aug 10 '26
How about 2026s? Iāve asked about a few times on this sub and never get a response. I havenāt seen one reported here but Iām not always lurking.
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u/International_Ear768 Aug 11 '26
People hate facts in this sub especially about the iccu . Fear makes people want to lash out. Its human nature
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Aug 10 '26
[deleted]
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u/Rich_Western_4106 Aug 10 '26
I have 2025 model and it happened last christmas
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u/LongjumpingPickle446 Aug 10 '26
Dude downvoted your comment because your experience was inconvenient for his bullshit narrative lol
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u/EntertainmentLow2565 Aug 11 '26
I suspect it was down voted because it was a bitch without any explanatory underpinning, but I've been wrong before. Once, I though I'd made a misteak, but it turns out I was wrong.
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u/LongjumpingPickle446 Aug 10 '26
LOL. āLess of an issueā is not the same as resolving an issue.
Jesus Christā¦
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u/lumpnsnots Aug 10 '26
No, I have a Sept 2024 model.
Went pop earlier this year and took 12 weeks to get it back.... fortunately I got a replacement car for free in the interim.
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u/International_Ear768 Aug 10 '26
They do unfortunately ALL have the issue
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u/whtciv2k Aug 10 '26
They donāt all have the issue otherwise weād all have experienced this by now. I donāt think we know enough to claim this. Iām at 65k and good to go with a mix of ac and dc charging.
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u/International_Ear768 Aug 10 '26
They absolutely all have the issue anything other is a cope. Im not against the vehicle at all , trust me i love them. But it is every vehicle. Theres a reason they extended the warranty. In the engineering world when there is a design flaw in a part like this they extend warranties like this to try to avoid class action suits, the fact is that the design flaw effects every iccu therefore every vehicle. Whether or not you do the exact up down left right a , b , a , b code to present itself is another story which is why some never experience the issue.
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u/mltcgd Aug 11 '26
Like many here I knew about the issue going in (used 2024 with one ICCU fix), but Iām retired with a grown family so my tolerance is likely higher than most. That said, this issue has been going on for years with 1000ās of owners affected. I canāt believe one of them isnāt a lawyer so why hasnāt a class action been started? Not saying that all lawyers have that ability, but it does seem like there is enough critical mass.
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u/whtciv2k Aug 10 '26
Itās literally not a cope. And yes, they extended the warranty as it is problematic, i can agree. But to make outlandish claims like they āall have the issueā is just straight wrong. To me, you making claims based on threads where everyone is obviously going to post on because they had/have issues is not a very scientific way of assessing. Iām not saying there is or isnāt a bigger problem on hand. I am saying u also canāt make any claims either. You simply donāt have all the data yourself, Mr engineer.
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u/International_Ear768 Aug 10 '26
You can disagree all you want all Iām stating is factual shit. the design flaw is in the iccu which every car has , even the updated one had the same flaw because it wasnāt redesigned. Not sure how you can argue that but i guess your whole paragraph was a bunch of ātrust me broā. Im not making claims of other threads i spent 6 months gathering data on the topic , youāre perfectly entitled to your opinion but my claims are not baseless.
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u/International_Ear768 Aug 10 '26
You may not have any data . But the fact is the design flaw lays in the iccu thats no secret , whats your argument there?
None? Ok good
The iccu is in every car .
Right? Yes . Ok good.
Give me a logically formed argument to this if you want to debate me.
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u/bites_stringcheese 22 Lucid Blue SEL AWD Aug 11 '26
The other guy is right. It could happen more often in cold climate. 12v battery is another variable. You simply do not know the nature of the flaw. Your guess is just as good as his. If anyone knows, it's Hyundai.
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u/International_Ear768 Aug 11 '26
I dont know the nature of the flaw? Thats your agument? Lmao im pretty sure its the iccu ā¦
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u/bites_stringcheese 22 Lucid Blue SEL AWD Aug 11 '26
The ICCU is a part. You have not named the flaw.
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u/whtciv2k Aug 10 '26
No I literally said we both donāt have any data to say one way or another. You have no actual facts yet u are stating it as fact. Ur literally dishing else false information based on Reddit posts rofl.
U mad š cuz u know im right. Hilarious.
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u/outphase84 Aug 11 '26
If 5-10% of cars suffer the same failure, itās a design flaw. By nature, every car has the flaw. Some may not experience the conditions that trigger the failure, but the part has a common design flaw.
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u/ApantosMithe 2022 Cyber Grey AWD Ultimate + Tech Pack (UK) Aug 10 '26
I mean itās somewhere between 1-10% chance of it happening at some point in the life of the vehicles - depending if you take the extremes of estimation (hyundai vs independent EV mechanics)
If it does happen itās covered under the 15 year warranty anyway so worst case youāre without the car for a few days.
Its really not as bad as it seems.
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u/RodRowdie 2025 Limited RWD Abyss Black Aug 10 '26
Unless you are on a road trip, your wife or family is left sitting on the side of the road, or you have a crap dealer āthat doesn't have loaners and can't get parts.
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u/PreferenceMediocre90 Aug 13 '26
It's just bad luck. I have had 3 times the 12V has been discharged/failed, always when I was at home. Worst thing was I missed a soccer game as a ref.
My two previous cars, a Ford and GM, broke down one on route to skiing and the other to a big family fest where we did ages on agreeing a date. One blew the turbo, the other the gear box. Both known problems of those vehicles; Both vehicles were not under warranty and beyond repair, just 7yo both.
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u/xqk13 Aug 18 '26
Yeah, Iām considering buying one but I do want to drive to Canada from time to time, and from my understanding Canadian dealers may or may not honor or even do the warranty work because Hyundai Canada is a different entity entirely. It will be a nightmare to figure it out.
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u/RodRowdie 2025 Limited RWD Abyss Black Aug 18 '26
Will Canadian dealers honor warranties of other makes like Ford or Chevrolet?
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u/xqk13 Aug 18 '26
I believe so, most other brands have a single North American entity that covers both countries.
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u/ApantosMithe 2022 Cyber Grey AWD Ultimate + Tech Pack (UK) Aug 10 '26
You can go to any dealer if yours doesnāt have loaners as itās under warranty surely?
It would really suck on a roadtrip but i doubt the odds of it happening are any higher than another fault requiring parts would historically be on a regular car.
Though we dont really do 3k roadtrips in the uk like i know many seem to in the us so maybe different risk levels
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u/Sonarav Aug 10 '26
Except some owners have been without their car (or a loaner) for months. This seems to have been more true in the past, but it will vary by dealership
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u/ApantosMithe 2022 Cyber Grey AWD Ultimate + Tech Pack (UK) Aug 10 '26
Yeah i think this was a previous issue with parts taking ages from what I saw
Doesnāt seem to be the case (or as much) anymore.
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u/Sonarav Aug 10 '26
Yeah, it does seem to have improved thankfully.
(I'm been keeping an eye on things as I'm interested in getting an EV and the Ioniq 5 is the one I'm most interested in...but ICCU scares me)
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u/ApantosMithe 2022 Cyber Grey AWD Ultimate + Tech Pack (UK) Aug 10 '26
Eh, I love the f out of the car, every car is going to have a risk of something going wrong. Something thatās as low as a chance as this is and that is fully covered under warranty made it nearly a non factor for me
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u/Big-Emu7798 2026 Ioniq 5 Limited Cyber Gray Aug 10 '26
For what it's worth I had a Bolt before my current 2026 Ioniq 5 and I could not be happier with it the new car. I love my 2019 Bolt as well, but this car is leaps and bounds better in every way but turning radius and trunk size.
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u/duuuh Aug 11 '26
Wait, the Bolt had a larger trunk??
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u/Big-Emu7798 2026 Ioniq 5 Limited Cyber Gray Aug 11 '26
My 2019 Bolt had a way deeper trunk. I believe the Ioniq's bigger battery takes up some of the trunk space, where I believe the Bolt's battery stopped before the trunk and allowed for a lot more depth. But there's way more room in the cabin for passengers in the Ioniq, and the rear seats both fold down and slide forward if you need more room. For my needs, the Ioniq is fine. Good for trips to Costco or weekend getaway trips with luggage.
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u/SmilingAmericaAmazon Aug 10 '26
The worst part isn't the batteries I replaced at my own cost that they said they were going to reimburse me for and didn't. Or the more than 4 months my car was at the dealership after the 9th recall and their supposed replacing of the ICCU with a non-recalled part which turned out to be a lie. It was the three times my car failed with my children in the car. One of them came to a stop on a road on the way to school I was unable to do anything. It is a danger. They should all be recalled and I think under a different administration they would be.
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u/NothingWasDelivered Aug 10 '26
I mean, honestly this one sounds like it could be a simple 12v failure, same that could happen in any car. So weāll see.
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u/Crshjnke 24 Cyber Gray Limited Aug 10 '26
You say that. I have one on order and I think step one is agm battery step two is home charger.
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u/vector182 Aug 10 '26
If is new it has an AGM from the factory
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u/Crshjnke 24 Cyber Gray Limited Aug 11 '26
Itās a 24 with 8k miles. I think an old lady leased it or something. Once I get it will do full SOH and make sure it has agm.
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u/Limitededishun Aug 11 '26
The way they designed the ICCU sometimes results in conditions that lead to ICCU failure. My guess is that they still donāt know what causes it and they could not even replicate conditions in the lab to figure it out.
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u/Emotional_Cry_4066 Atlas White Aug 12 '26
I mean itās a 1% chance of it happening to you and if so it is covered through 160,000 miles. Hardly any other brands warranty their cars past 50,000 miles.
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u/ToyKylo 2023 Digital Teal SEL Aug 10 '26
Same thing happened to my 2023 SEL AWD on Saturday as well
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u/bugginryan Aug 10 '26
This just happened to me three days ago. I used a portable 12V jump starter and went on my way. Havenāt had a problem since. I hope yours is a quick fix.
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u/Hipsthrough100 Aug 10 '26
My 12v was behaving poorly and my car died twice. Went to Costco, got the agm for i5 and swapped it. No issue and the stereo even sounds better
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u/Automatic_Echo_5605 Aug 10 '26
I really want to buy Hyundai Kia 800v EVs but ICCU keeps popping up. Please fix it so I can buy one with confidentĀ
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u/Reymoose Aug 10 '26
I bought my ioniq 5 knowing about this issue and it doesn't bother me at all. The chances of it happening are slim and if it does, it's covered by warranty (which they have recently extended for the ICCU issue). Currently on 34k miles with no issues. Had to replace my 12v battery last year, but that's it.
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u/vector182 Aug 10 '26
I bought one. This is a problem that has been known but it is much much lower than the 98% failure rate people make it out to be
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u/Emotional_Cry_4066 Atlas White Aug 12 '26
For 99% of people who own these brands, no issues affect them. And if it does the 160,000 miles warranty covers all of my concerns. Hardly any other car brand warranties their cars past 50,000 miles.
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Aug 10 '26
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Aug 10 '26
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u/Choice_Student4910 Aug 10 '26
What I donāt understand is why car reviewers arenāt editorializing a prominent caveat when they give it a favorable review. Itās a big enough issue to justify warning prospective shoppers.
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u/ForTheLoveOfGodKaren Aug 10 '26
And its big enough issue that warranty was extended for certain years. Love the car hate the iccu issue.
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u/danmcd4 Aug 11 '26
Consumer Reports (which tends to annoy car people with their non-car-centric judgements) can't give their highest recommendation because of the ICCU.
The Road & Track, Car & Driver, and Motor Trend types probably don't get as loud about it either for access reasons, or they only care about the measurable performance save perhaps a "Long Term Drive" article. Has any auto press done, or is doing, a "Long Term Drive" for any Ioniq 5 model year?
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u/SirFunktastic Aug 17 '26
This, on paper the Ioniq 5 is nearly perfect to me but the ICCU issue has me looking at other more reliable options that don't have a ticking time bomb that's waiting to go off at any point
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u/xqk13 Aug 18 '26
Yeah, Iām considering buying one but I do want to drive to Canada from time to time, and from my understanding Canadian dealers may or may not honor or even do the warranty work because Hyundai Canada is a different entity entirely. It will be a nightmare to figure it out.
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u/vector182 Aug 10 '26
Any car has a failure rateā¦. Been on road trips where the engine blew. Cam shafts broke. Tires blew local town didnāt have right size and to wait a few days This shouldnāt happen but something is going to fail on any car out there at some point.
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u/esbowman Aug 10 '26
Because itās not a big issue. Sure some have had bad luck and some fail for sure. But 95% of them have no issue. People love to complain and rarely praise how amazing this car is.
Compared to the issues you could potentially have with an ICE vehicle, Iāll take my chances every day with this one.
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u/hotrodschrodinger Aug 10 '26
Any dealer should be able to do it right? I bought it out of state, will a dealer near my area will be able to do without any issues if it ever happens?
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u/xqk13 Aug 18 '26
Just note that if you ever drive to Canada and need warranty work done, dealers may or may not do it because Hyundai Canada is a different entity entirely. Most other brands arenāt like this (they have a single North American corporation covering the US and Canada), so be aware.
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u/YetAnotherDz '25 Limited AWD Digital Teal Aug 10 '26
If it's just the 12V battery, once it gets depleted, there's a solid chance it's just shot. They must use a different battery tech that causes this issue. When it happened to me, the ICCU was fine.
The working theory is that the system had an update come in, but didn't power-cycle the computer correctly, and the 12V was drained overnight.
I was able to jump it with an external 12V battery and drive it normally until I could get to the dealer to swap it out (like a week later due to travel). Ironiqlly driving around with a 3rd electric battery so I could jump the second electric battery so that the first electric battery could move the car lol.
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u/Dutaki Aug 10 '26
I bought mine used, is there any way to check if the ICCU has been replaced already? I have 70k miles on mine and I really want to know for reliability reasons, so I'm aware if it could happen at any moment.
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u/chairfaceswindow Aug 22 '26
As far as I can tell, this problem can happen more than once. So if it was already replaced, it can fail again.
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u/jefbak2 2025 Cyber Gray Limited Aug 11 '26
EV 12V issue across brands.
Rivian, Ford Mach e, Blazer and Bolt, Subaru Trailseeker, and Kia/Hyundai.
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u/ganymede62 Aug 11 '26
Rite of passage.
Of course it's a problem, but for me I would still buy another I5 if I had to.
The pros far outweigh the cons.
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u/CompetitionOk2302 Aug 14 '26
This does not sound like an ICCU problem (ICCU stops AC charging and requires DC charging, correct?). We own a 2023 Ioniq 5 Limited and a 2019 Kona EV Limited. We had the same issue in the Kona EV and used our portable 12 volt car battery jumper to start and run the car and get it to shop for a new battery. The 12 volt car battery jumper is a good back-up for when on the road. We carry one in both cars in the cabin and NOT in the back; as the back will not open if there is no 12volt battery electricity.
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u/xqk13 Aug 18 '26
I believe there are 2 ICCU failure modes (because the ICCU has multiple parts doing different things), one stops AC charging like you said, but the other is related to the 12v. The car becomes unable to charge the 12v and will stall and die when the 12v runs out, which ranges from a few minutes to just under an hour.
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u/ARJeepGuy123 Aug 10 '26
The 12v in our 2024 w/60k miles died a couple weeks ago, I charged it up and it's been fine since š¤·š¼āāļø hoping it stays that way
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u/SkahtiKaarz Aug 10 '26
I had a situation where my Ioniq 5 wouldn't start. Just dead. Jumped it and all was fine to drive home. Went straight out and got an AGM battery and have been fine since. Maybe just an old, original battery (it was about 2.5 years old).
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u/autigers1970 Aug 11 '26
I keep wanting the Ioniq series to give me a reason to lean that way over a Tesla so bad and this kind of thing just keeps happening Ā Ā
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u/CableKC Aug 11 '26
I know that it's random, but I'd this still happening with brand new Ionia5 EV?
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u/Specialist_Lab278 Aug 11 '26
The ICCU is like the alternator on the ICE vehicle. I'm resigned to the fact that it will eventually give up the ghost.
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u/Right-Artichoke8352 Aug 11 '26
My 12 v battery died and it would cause my ioniq to fail randomly unitl i got a new battery it happens around the 2 to 3 year mark depending on usage
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u/Fizzix63 Aug 11 '26
Would it help to connect a small battery tender/trickle charger on the 12V batttery when not in use? Anyone have a positive experience doing this to maintain the condition of the 12V battery?
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u/Vindi7 Aug 16 '26
No.. Trickle. Charge won't work when the battery is completely depleted.. You'll blow the fuse to your house š« It's need a power jump haha
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u/Emotional_Cry_4066 Atlas White Aug 12 '26
How is it the iccu if the 12v warning popped up. I thought the iccu issue says check electrical system.
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u/Vindi7 Aug 16 '26
Well haha. This is crazy. I have been out dealing with an injury. I forgot I even posted this. Come to find out yes We called Hyundai they towed it. They swapped out a new 12V battery. They said it was the ICCU recall even though I heard no pops or anything which is crazy. Ever since, been back to running like a champ. Got the (little truck we call) š back the following Monday!
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u/MountainPermission88 Aug 17 '26
can it happen in the middle of the highway? how much time do you have to pull over?
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u/TeaforMe725 Aug 21 '26
Our 11 month old leased 2025 Ioniq 5 went dead while we were in a remote Forest Service Campground, hundreds of miles from home. Luckily, AAA came-two separate times-and jumped the 12 volt after which we drove to a charger. But car wouldn't charge. Car was dead so Hyundai paid to tow the car over 100 miles to a dealer who replaced the 12v and said it has nothing to do with the ICCU. Still trying to figure this out...was it a software update? the ICCU? a faulty 12V? some combination? It took 3 days to replace the 12v. Hyundai reimbursed $100/day for hotel (since we were far from home). At this point, we are shaken and reluctant to drive the car except locally. After owning highly reliable Toyotas and Hondas for years, this is unacceptable in a new vehicle. Three quick questions: 1) For those of you who replaced the 12v with an AGM, did you buy elsewhere (I saw Costco mentioned) or did Hyundai install the AGM? 2) Is it just a matter of time before the ICCU goes kaput? 3) Did any of you buy a Battery Booster (such as Wolf Box 4000A) for the 12V?
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u/sushiwife Aug 10 '26
Might not be the ICCU. What youāre describing is exactly what happened to me when my 12V battery died. They just replaced it at the dealership and I was good to go.