Digital Car Keys May Not Transfer When You Upgrade Your iPhone

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Originally published at: Digital Car Keys May Not Transfer When You Upgrade Your iPhone - TidBITS

Amid all the fuss of verifying my credit and debit cards in Apple Pay after switching to an iPhone 18 Pro (see “Notes on Setting Up a New iPhone 18 Pro and Apple Watch Series 12,” 21 September 2026), I didn’t notice that my Hyundai IONIQ 5 digital car key was missing (see “Living with Digital Key 2 on the Hyundai IONIQ 5,” 6 April 2026). Nor did I notice it was missing the first time I drove the car because Tonya was with me en route to the weekly workout I coach, so her iPhone served as the car key. I only realized what was going on when I tried to unlock the car after the workout and nothing happened. (The other giveaway was that I had to choose my profile manually after turning the car on to reset the driver’s seat to a position where my knees fit. I feel like I’m in a clown car when the seat is adjusted for Tonya.)

In retrospect, this shouldn’t have surprised me. Digital car keys are generated and stored in the iPhone’s Secure Element and are bound to the vehicle identifier and public key. Given this architecture, I initially assumed digital keys couldn’t be transferred between devices. However, Apple’s documentation indicates that transfer is possible—but only if you explicitly select the car key during setup. I didn’t inspect the Wallet category during setup because I wanted everything transferred and assumed it would all be selected by default.

Apple instructions for transferring digital car keys

If, like me, you lose a digital car key while transitioning to a new iPhone, it’s easy enough to recover manually. First, I went to the digital key screen in the IONIQ 5’s infotainment system and deleted the old one. To reduce the chance of confusion, I also deleted the old digital key from the iPhone 17’s Wallet app.

Then, starting in the MyHyundai app on my new iPhone 18 Pro, I ran through the steps to create a new digital key.

It handed off to the Wallet app, where I had to go through several additional screens, plus a few more to add the digital car key to my new Apple Watch Series 12.

In reality, the first try failed for reasons that were never clear, but restarting resolved them. Restarting the car, that is. I can’t tell you how amused I am that fixing the problem required power cycling a 2.4-ton vehicle.

Dialog: Please restart your vehicle and try again. If issue persists call Bluelink Support. OK button

I will admit I’m a little disappointed there was supposedly an easier way to transfer the digital car key, but regardless, Apple should surface digital car keys more prominently in the Quick Start transfer process rather than burying them as an option inside the Wallet category.

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Similar issues arise with Digital Driver’s Licenses and other Digital IDs. As I mentioned in my previous write-up, the California DL wouldn’t transfer, so I deleted it from the old phone and recreated it from scratch on the new phone. That involved scanning both sides and then running through a series of photos to prove it was a live metrying to add the ID to my iPhone. The Passport ID transferred the information from the old phone, but I still had to go through the photo exercise to show it was a live version of me doing the transfer.

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IMO when you’re upgrading an old device to a new one it should default to moving everything over unless you tell it not to. When I replaced my Series 7 watch with a Series 12 last weekend I wanted the new watch setup exactly like the old one (as much as possible, anyway), and when I buy a new phone it’s the same. If there was something on the old phone I didn’t want I would have already deleted it myself.

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Should I assume that there’s a menu item somewhere to reboot the car’s computer systems?

I hope you don’t have to disconnect the battery, as I had to do in order to reset the infotainment system in my 2012 Honda.

On my wife’s 2018 Kia, there’s a switch on the fuse panel that disconnects the electronic/computer systems from the battery. Its intention is to prevent the background systems from draining the battery if you leave it parked for an extended period of time, but it also works for rebooting those systems if you just flip it off for a minute and then turn it on again.

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The more electronic controls and security systems, the more we’re going to bump into problems. Yesterday I got an electric bill that reminded me the electric company had just installed a smart meter that I could use to monitor how we use power. Setting it up required the last 4 digits of my SS, which seemed invasive, but was only four digits. It didn’t work. After 20 minutes of waiting on the phone, the problem turned out that both my wife and I are in their records, but only my wife is on the master digital record, so I had to put in the last 4 of her SS on a screen with my name on it. Somewhere down the line, I’ll bet that’s going to cause problems.

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Yes, I need to redo the Digital ID, but it wanted to take live photos of me, and I didn’t want permanent photos to have the road rash on my face. :grinning_face: I didn’t comment about these IDs, mostly because I have never found a single use for them in the real world.

No, I just turned the car off and back on. As far as I’m aware, there isn’t a restart command within the infotainment system.

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This may be a branch in the conversation, but I think this is indicative of just how messy our databases are. They are probably getting better as more people are individual units and databases rather than families, but I still don’t think that many companies pay much attention to data cleanliness.

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In my 2023 Prius, there is a button below the screen to control the audio volume. Pushing it in mutes the audio. Pushing it in and holding it until the screen goes blank reboots the entertainment/internet connectivity system. I have done this reboot when my Apple Play or Bluetooth connectivity goes wonky, and it has always worked.

I suspect that most recent Toyotas work similarly. If your car has a similar button, try it.

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Does that lead to a loss of any settings?

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No, everything comes back. It’s just like the initial boot when you start the car.

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Is it then any different than just stopping and starting the car again?

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The convenience is that I don’t need to stop and restart basic car functions by turning the car off and back on. My passenger or I can start it at any time. The passenger (or I) can start it even while the car is moving.

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What could go wrong with rebooting the car’s brain while driving? :grinning_face:

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I’d like to hope that the radio and the engine control systems are on different processors. But these days, who knows.

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I’ve had to reboot my 2015 Tesla while driving; I don’t remember why, but I judged that getting whatever was broken to work again was safer than trying to pull off the road. The most disconcerting thing was that the dash was dark and the turn indicators didn’t make any noise, though I believe they were actually flashing outside the car. (I’m kind of fanatic about turn indicators; it made me anxious to think they might not be working.) No nav or entertainment, of course. But the car kept going forward (without a dashboard speed display), and the brakes and steering continued to work. Had Tesla had their way, I would have lost rear-view mirrors, but NHTSA wouldn’t budge on the requirement for physical mirrors.

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Sounds like your case illustrates well how the regulator was right and Tesla wrong about that.

I’m surprised though that regulators appear to think it’s OK for a car’s software to be able to crash in such a manner that although the car will continue to drive, it just no longer will tell you how fast you’re going. Then again, judging by how bad blinding has gotten, it appears regulators have more recently been quite hands-off (to put it mildly) in several aspects.

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I’m not rebooting the car’s brain. I’m only rebooting the functions that primarily appear on the entertainment screen. That includes the various audio tuners, audio processors, Bluetooth connectivity, AirPlay, Android Auto, and Toyota’s equivalents. None of these control the car’s movement, handling, climate, or safety features.

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What does turn off when the power fails in an electric car? From my experience, the life-savers are the brakes and the steering wheel.

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It’s my understanding that there are two electrical systems. One that drives the motors and is powered by the large battery banks. And one that powers everything else, which is powered by a traditional car battery, kept charged by the propulsion electrical system.

If the big battery system fails, you’re going to lose the ability to accelerate and should pull over as soon as possible, since it’s the equivalent of running out of gas.

If the auxiliary power system fails, I hope it will behave like an electrical system failure in a gas car where the manual/hydraulic linkages continue to work without power, but I haven’t researched this.

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Yes: in my Tesla (first an S, now a 3), you can hard reset the car’s software while driving and it will still function as a car exactly as you would expect, though you will lose the speedometer of course. The reverse is also true: I have had the 12V battery fail (while parked) without warning on both. (The 3 is supposed to warn you in the app; I was not warned.) That bricks the car completely, though there is supposedly a hack with a 9V battery and contact points under the bumper to get it started which, just like a gas car, will then work until you stop and turn it off. So, you could plausibly get to a service place to get a replacement battery. Alternatively, that gives you enough juice to pop the hood (software, no accessible hardware switch) which is where that battery is located. Seen the YouTube video; not tried!

I was surprised to hear about this 12V lead-acid battery but I believe it is a mandatory safety feature. I am mildly curious to know if it is lead-acid just for ease of getting a replacement, or if it is not permitted to be lithium?