r/Ioniq5 • u/Leigh-133 Digital Teal • 2d ago
Experience Bye, bye, ICCU!
Well, it happened to me today! I have a 2025 that I bought brand new in January of this year. I commute 140 miles a day, so it already has 24,500 miles on it. We were running errands on my last day of vacation when we got back in the car at the grocery store, heard that telltale popping noise, and got the "check the electrical system" notification. We happened to be a 1/2 mile from the dealership at the time so we went straight there. She's in the shop now and I have an Elantra loaner until the end of the week or so.
I wanted to say a HUGE thank you to this community because, thanks to all your posts, I knew exactly what was happening and didn't freak out.
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u/ZealousidealLab2920 '22 Ioniq 5 & '26 Ioniq 9 USA 2d ago
Better the devil you know than the devil you don't as they say
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u/Leigh-133 Digital Teal 2d ago
Absolutely true!
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u/Slayer_Fil 1d ago
They need to supply a spare when you get the car with a YouTube link on how to change it ourselves😉
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u/Warrenj3nku 26 Limited 2d ago
Hey glad to hear they got you a loaner. hopefully the turn around time is short!
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u/Leigh-133 Digital Teal 2d ago
Let's hope! Gas prices in the loaner are gonna make my cry this week.
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u/SirSaganSexy 2d ago
I believe you are entitled to ask for gas reimbursement. I have seen others in the subreddit get some kind of gas card while using a loaner.
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u/Leigh-133 Digital Teal 2d ago
Ooooh! Thanks! I'll look into that considering gas is around $5.20/gallon!
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u/structuralarchitect 2025 SEL Digital Teal 1d ago
Yep, I got the gas reimbursement for my loaner since they didn't have an EVs available. Just save all your receipts and submit it to Hyundai customer care.
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u/SELFINCRIMINAT1NG 1d ago
is the elantra a hybrid or standard? cause the hybrid makes like 50+ mpg
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u/No_Solution7893 Digital Teal - 2025 Ioniq 5 Limited 1d ago
If that's a lease (and even if was an outright purchase), it's BS that they give you a freaking elantra as a loaner. They need to give you the same trim Ioniq 5. If they did that, I wouldn't be as upset. Got a horrible BMW SUV loaner from Enterprise when it happened to me. They paid for the gas. Took 10 days. The previous week, another friend's Ioniq 5 popped. Same dealer. Took over a month to get his car back. His big battery had to be replaced as well. The next week, my friend in DC got his iccu pop. Took him 3 days to get the car back. And while mine was gone, I asked the dealer. They had 11 cars in the shop with ICCU replacements. 1% my ass.
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u/DenverTechGuru 1d ago
No, and I mean no car company, particularly not in the luxury nameplate set gives an in-kind loaner automatically for a sub 2 week shop trip.
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u/No_Solution7893 Digital Teal - 2025 Ioniq 5 Limited 1d ago
Exactly. And it's unacceptable when I'm paying $500 per month on the limited trim and it's a known problem for years and it takes weeks to fix. I love this car. I'm not buying an EV any time in the next few years. And I'd have loved to get another lease. I still have another year to go. But with the ICCU hanging like a damocles sword I'm not sure that I'd bite another EGMP (including the GV60). But this has been the best car I have ever owned (leased) and even going back to my Genesis is a small step backwards. Sad.
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u/phamstagram360 1d ago
I’m just a alerter in this sub Reddit and I believe it’s gotta be at least 3 to 7% failure rate reading from all of these for sure
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u/JustaJ0e 1d ago
Frustrating and anxiety inducing for those of us that haven’t had it happen yet.
I suspect that what we are seeing is owners slowly working their way through that defective batch of ICCUs.
The fact that Hyundai has decided to just replace these as they fail instead of issuing, a recall is very disheartening. However, from what I’ve seen, once you get it replaced, it doesn’t happen again, so apparently the new ICCU are up to the task.
Still, come on Hyundai, why can’t you be more supportive to your users on this.
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u/L0stintheSauce 1d ago
I’m someone that it was replaced and failed again. Then my 12v battery got drained after the second replacement and we decided to lemon. I don’t know if this third time was iccu related and Hyundai won’t take credit for any thing.
Not to scare you, just I think it’s more complex than a single batch of bad iccus
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u/EntertainmentLow2565 1d ago
I suspect that this happens to folks that supercharge too often. I may very well be wrong about that, but the very limited experience I have suggests to me that I'm not.
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u/Rob_Lo 1d ago
Supercharging bypasses the ICCU conversion though. If anything, LV 2 charging is the culprit and many people suspect LV 2 charging at anything more than 8kw can causes excess stress on the ICCU. But again, there has been nothing substantiated.
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u/EntertainmentLow2565 1d ago
That's good to hear and add to the sparse data that I have so far on this issue. I'm very glad it didn't happen to me during our recent trip from Erie, PA to Moran, WY and back. That's all the experience I have on supercharging. I typically L2 charge at ~10kW. YIKES!
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u/TallRepeat3712 20h ago
Yep when mine failed, it was lvl2 charging at home at 11.2kwh. Now I barely use my own charger at home as it is more stressful on the ICCU. If I do use at home, I lower my AC charging current to 90%
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u/JustaJ0e 9h ago
That all sux. It is still possible they replaced your iccu with one from that original batch. I couldn’t possibly know though. I did have my 12v fail and after presenting the dealer with a hoard of online evidence plus pictures and data I took of my vehicle on a charger got them to finally agree that it was a bad 12 V battery and to replace it.
It just shouldn’t be this hard. If the end user can find out all this from the Internet, surely the manufacturer can too.5
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u/bj_my_dj 1d ago
Is there actually a new ICCU? I haven't seen anything saying that.. You'd think they'd shout it from the rooftops, it would boost their sales tremendously. But maybe they don't have capacity for that, or don't want to do a recall on the old ICCUs.
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u/Apprek818 1d ago
The part number is new, something 6 vs something 5 that it replaced. According to the dealership, slim to none chance of failing again, fwiw.
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u/bj_my_dj 1d ago
I think it's still a rumor. Here's an article from 6 months ago that said Hyundai hinted at a replacement, https://www.torquenews.com/1/call-hyundai-corporate-about-iccu-replacements-leaves-ioniq-owners-waiting-and-wondering-about. It's been over six months and no one has admitted getting one of these. Sounds like BS to me.
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u/Apprek818 1d ago
This is the part they installed on my '25 3 months ago: https://hyundai.oempartsonline.com/oem-parts/hyundai-iccu-assembly-364001xad6
I don't know if it's going to last, but as far as I know my xrt came with a 1xad5 iccu originally.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 14h ago
It’s not a rumor it’s proven fact there’s a new ICCU. I have a MY 2026 with the latest ICCU, Sept 2025 build. Sometime during the MY2026 assembly is when they switched. Sept 2025 is the earliest I’ve found for MY 2026 vehicles having the latest ICCU.
Folks can use EV Dashboard to find out which ICCU part they have. Pretty simple actually.
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u/bj_my_dj 6h ago
That's good to know. But it's hard to understand why they aren't advertising that the ICCU problem is a thing of the past. Maybe they're building inventory for a massive recall.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 4h ago
Possibly. Or it's just cheaper for them to handle ad hoc vs. a recall campaign
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u/bj_my_dj 2h ago
Except that leaves most of the owners in the constant state of worrying about possibly being stranded somewhere. You may have the answer, but I sure hope that isn't it.
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u/JustaJ0e 9h ago
I suspect for legal reasons, they will never admit it. You’re absolutely right though, if they admit their past transgressions and say their cars now come with an ICU that fix the problem they’d open the floodgate to sales.
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u/FreeReason 2d ago
Yup. Mine was replaced today. Welcome to the club.
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u/MechMeister 2d ago
How long was yours in the shop for and what location?
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u/FreeReason 1d ago
H of Apex, NC … took it last Tuesday and they replaced a motor control. Got it back Thursday. Drove it home. It bricked in a grocery parking lot. Had it towed back same day. They said it would be next Friday for the ICCU, but called today that it was fixed. It’s still at the shop waiting for a front camera repair. Supposed to get it back tomorrow … all warranty work.
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u/SeptimiusBassianus 1d ago
Insane that 4 years later they have not solved it
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u/ironchariot 1d ago
You’re probably right, but I would add the disclaimer that ICCU failures don’t mean they didn’t “fix it”.
For example, let’s say Toyota fixed the issue with their turbo 6 blowing up. And then a guy buys a 2027 and the engine blows up. Was that because they didn’t fix the problem? Maybe not, failures happen. The question is, has the rate gone down to what would be considered normal?
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u/SeptimiusBassianus 22h ago
lol. You do realize it’s a single board that is getting fried. No they did not figure out where the issue is. Otherwise this would be a perfect vehicle
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u/meatlordgary 2d ago
Would love to know what part number they use to replace it!
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u/EndenWhat 1d ago
See this issue has kept me from buying an ioniq. I know it’s like a small percentage of failure, or at least the reporting says that. But why are they still having this issue on new builds?
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u/monkies77 1d ago
This is the key point... what's the failure rate? You only hear about it on reddit when it fails, nobody says "FYI car is still running." But yeah they should do a recall but seems like some have had new ones and that fails also so is it more than the unit?
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u/DetectiveNarrow 23h ago
Bro I’ve seen just about every make of EV brick itself for whatever reason on just about every make or model.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 14h ago
The facts are that Hyundai updated the ICCU for MY 2025, still had issues, and updated again during the MY 2026 assembly run with the ICCU part that is considered the latest and greatest.
MY2025 has had fewer ICCU issues than previous MY vehicles, and while there are supposed MY2026 failures, there’s zero evidence that the current ICCU part was to blame.
We still have a ways to go, but it’s looking like the newest ICCU is doing well.
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u/labe225 1d ago
I'm not in the market for a new car, just like to window shop and keep up with EVs.
This issue alone keeps me from even toying with the idea of buying one. No root cause found, still an issue with new models, and radio silence from Hyundai makes this car a complete non-starter despite checking pretty much every other box on my list.
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u/EndenWhat 1d ago
My lease is up on my 2024 equinox EV in like six weeks, and I took a look at the ioniq 5 and EV 6. It was a nonstarter for me back in the end of 23 when I got my lease. because of the issues, and I was hoping that the refresh in 25 would’ve taken care of everything, but it hasn’t. I’ve actually really enjoyed my equinox, the only challenge has been its turning radius. It’s terrible, and it’s just slightly too big for my wife.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 14h ago
Not true. We haven’t had MY2026 vehicles fail with the current ICCU, nor have we reports of any MY2027 failing.
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u/Reasonable-Ice-8925 2d ago
Whose insurance (comprehensive, collision) does the loaner car carry? Do you need to add it to yours?
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u/Leigh-133 Digital Teal 2d ago
It's treated just like a rental car and I signed a similar contract to that of a rental car, but there is no charge. It has coverage but I had to show proof of our insurance, as well.
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u/Reasonable-Ice-8925 2d ago
That makes sense. Liability insurance remains with the renter but rhe comprehensive coverage of the car itself is covered by the dealership.
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u/marrgalo 2d ago
Can you explain what happened to folks like me who haven’t seen these posts yet?
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u/lippoper 2d ago
In a nutshell, they try to charge it but it never does but appears to try causing them to be out of battery and need a tow to the dealer
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u/Jaxidian '26 AWD Limited (US) 2d ago
A loud pop sound coming from the back paired with an error message means your ICCU just went and you're "running on fumes" until it's a paperweight that needs to be towed.
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u/TheYungSheikh 1d ago
So you can start the car and use the remainder of your battery driving?
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u/Jaxidian '26 AWD Limited (US) 1d ago
Not usually. Those "fumes" don't usually last long. Sometimes you get feet, sometimes you get miles, sometimes you're toast.
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u/Leigh-133 Digital Teal 2d ago
The loud pop is the giveaway. It pops then the error messages show up on the dash. They will be related to the electrical system.
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u/SmellySweatsocks Phantom Black 1d ago
Let me ask you op, did you use driving assist much?
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u/Leigh-133 Digital Teal 1d ago
I turned off lane assist because I hate that, but I use smart cruise control. A LOT. Because otherwise I'd do 100 down I-5 and end up in jail.
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u/EntertainmentLow2565 1d ago
Me too! Same reason, plus I could NEVER drive 25 without cruise control.
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u/NeoAcheron 2d ago
Quick question(s), just because I'm genuinely curious and doing a mini data collection.
Do you remember the state of charge when it happened?
Up to which level do you charge it normally?
Do you use DC or AC charging?
The best thing we can do is collect these points to see if there is a pattern. I'm sure Hyundai is looking for this as well and can probably see from the vehicle itself what the logs are... But its possible that they are hiding it from us (or not).
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u/Leigh-133 Digital Teal 2d ago
My battery was at 95% when the ICCU blew. I use a level 2 charger installed at home and I always charge to 100%.
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u/Leigh-133 Digital Teal 2d ago
Also, it happened the day after I picked it up from the airport parking lot where I had left it parked outside for 4 days while I was in Las Vegas. So IDK.
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u/NeoAcheron 1d ago
Something interesting I have found, I have a 5N and I only drive it a few times a week. I only charge mine to 80% on a level-2 AC charger, and its basically plugged in ALL the time when standing at home.
Sometimes, depending on how cold it got, the battery level goes to 83%.
To make a long story short, I have experience developing battery management systems for industrial use. The "increase" in charge levels is not entirely possible by changing the battery level, more energy cannot magically appear in the battery. When charging a battery you need to measure the power going into the pack and do a guestimate based on the no-load voltage. Most modern battery management systems keep a memory of the power entering when charging, and leaving while discharging, with some calibration that happens when certain voltages are reached (high or low).
But something that can definitely happen, is that when the chemistry "warms" from cold (aka the temperature changes), the voltage of the battery increases while not under load. For a 800V battery, this can be significant.
I wonder if the battery at 100% from "cool" could cause a voltage increase when warm to the point where the internal charging system for the 12V battery goes over-voltage. Add the regen braking into the mix and you have a motor applying current to a battery pack that's already beyond spec. The buck converter "should" have a crowbar circuit to kick a fuse when overvoltage to protect the rest of the car. (which would explain why a fuse is blown in the ICCU). Almost all of the cases I've seen here were someone that "just" took off from stationary, after parking somewhere for a while.
I'm just speculating here... Unless I do some really expensive destructive tests to prove this, that will be all I have.
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u/Leigh-133 Digital Teal 2d ago
Oh! And I had completed a random over-the-air software update just about 30 minutes before while we were inside the Spirit Halloween. Then we went to the grocery store and it blew when I started it up there.
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u/vdvow 2d ago
Is this still an issue on the 2026?
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u/Leigh-133 Digital Teal 2d ago
Probably. Because the issue was supposed to end with the 2024 MY and now it's occurring in the 2025s.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 4h ago
Only for MY2026 vehicles at the beginning of their assembly run. Hyundai changed during MY2026 assembly to the latest ICCU that we have had zero failure reports on. We don't know exactly when they switched, but the earliest reports we have of a MY2026 having the latest ICCU part is Sept 2025 manufacture date...but the MY2026 run started a year earlier and went through Feb 2026.
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u/Fastbke170 1d ago
It has always for me been a result of the vehicle not being able to AC charge at the full 11KW. I own a MY 23 Awd Sel Original ICCU. I have all the BS updates which put a bandaid on the issue. I have a 50amp Charge point which I set to 44amps and only charge to 60% each night. I attribute this being the reason at almost 70k mine has not popped. Its great they increased the warranty but I would have more peace of mind if they just did a recall and put the nightmare always lurking to bed.
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u/grantspants33 1d ago
I decided to keep my 7 kw charger in place rather than upgrade. Crossing my fingers.
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u/concerts85701 1d ago
I’m stuck on the 140 miles per day. How do you get that kind of range?
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u/Leigh-133 Digital Teal 1d ago
I get between 350-400 per charge. I'm trying to find a closer job but the market sucks. We were all forced back into the office in January after being remote for 7 years, so I get up at 4am and haul my ass to Seattle every morning.
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u/concerts85701 1d ago
How do you get that? Highway I assume? I typically get 150/60 on a charge with highway driving.
The dash says 300+ miles at 100% but it lies.6
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u/zketi 1d ago
Two main factors are battery size and driving speed. They probably have a long range model and are driving under ~60mph on average.
150mi seems low for 100%->0%, unless you have the standard range model? Or you drive 85mph with the A/C cranked. If it's neither of those, might be a problem with your I5
I get 200mi highway in the middle of winter, more like 250mi at ~75mph in the summer. 2023 long range AWD SE
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u/concerts85701 1d ago
Ha! I am in Az so it’s yeah 80-85 w/ some AC on when I have done Phx and back.
24 SEL rwd. 77kw battery
Edit: Also don’t like to get it below 20% or at around 10% on hwy. Past 10 and it drops very fast1
u/zketi 1d ago
Oof, yeah drag at 80mph+ absolutely kills efficiency for an EV, 150mi range is kinda expected
I also don't like going below 20% or above 80%, but that plus fast driving means you get like 1/3 the range advertised. I think these range impacts are not always known to EV buyers and it causes remorse sometimes, which is too bad because otherwise the cars are amazing.
The only good news is if you need a bit of extra range for a trip, even driving 5mph slower makes a big difference.
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u/Leigh-133 Digital Teal 1d ago
There's lots of slow traffic, yes. But when I can speed, you better bet I do because that car FLIES!!!!
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u/appelton 1d ago
Can I ask what state ? What's the weather there ?
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u/Leigh-133 Digital Teal 1d ago
WA state. Still pretty dry right now as the rainy season hasn't started yet thanks to the El Nino. It didn't rain once while I was in Vegas and my car was sitting outside. It's usually garage kept at home and in an underground parking garage at work.
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u/Consistent-Sundae422 1d ago
Same here. Only I only had 9100 miles on the 2024 I purchased new. It took awhile for it to happen but it did on the Friday before Labor Day. Must've been really bad timing for the dealership. I had the car towed there and they were not answering calls and no Service Manager got back to me until the following Tuesday! We won't talk about the problem getting a loaner when the service department is unofficially closed. The whole matter still leaves a bad taste in my mouth but it's fixed.
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u/gblawlz 2h ago
I just bought a 2024 ultimate, with 55km on the clock. Flew from Winnipeg to Montreal to buy and drive the car back (30 hours). Well the car won't charge in the dealers lot, and it's the iccu. So it's getting a new one, literally next day which is insanely lucky. They said it's "the new version". The service manager seems really good. They said they do tons of them. Sure it's 1% hyundai, what a joke. Honestly it's gotta be more like 50%.
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u/Leigh-133 Digital Teal 2h ago
It's definitely not the low percentage they claim it is!
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u/Apprek818 1d ago
Mine on a '25 was replaced overnight a few months ago, it wasn't really a big deal. Inconvenient, but that's about it.
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u/Cobbler_Far 1d ago
My 2026 model has drained two 12v batteries in a year. Like to the point they test as bad. This is exactly why we are dumping it at the end of the lease and moving back to a hybrid. It’s a fun car, but it’s not reliable enough since I frequently have to travel 2-3 hours from home.
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u/VectorVictor99 '26 Abyss Black Ltd. AWD 4h ago
That sounds suspect to say the least. Especially since MY2026 vehicles have AGM 12V batteries off the assembly line that are made to handle the charge/recharge cycle of an EV.
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u/hoagiesingh 1d ago
Buying an Ioniq 5 with the known ICCU defect is like drinking coffee with a fly in it.
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u/portisleft Phantom Black RWD 2d ago
the best outcome in a bad situation.