Why is my key hot after taking it out of the ignition?
“It’s probably always hot,” you think as you step out into the parking lot. “I just never noticed before. Yep. A nice, hot, very normal, car key.”
But you know, of course, that that isn’t right. And so, with a sigh, pull out your phone, and type in the question that brought you here.
So, why is your car key hot after taking it out of the ignition?
An electrical short could be the culprit behind a hot car key. When electrical elements become damaged they begin to generate heat. If that short happens close to the ignition, it could cause your key to get hot.
Sorry. Probably not the answer you were hoping for. All is not lost, though. Even electric problems can vary in terms of their scope and severity. Below, we explore possibilities, dispel myths, and talk next steps.
Read on as we take a more in-depth look at what can cause a car key to heat up.
1. Electrical Shorts Can Cause Hot Car Keys
Probably the most urgent and troubling reason a car key might feel hot to the touch after being removed from the ignition is electrical failure.
Electrical failure happens when the connection between conductors is compromised in a way that creates an excessive current flow. In other words, the wires start getting hotter than they are supposed to be.
As an added note—this is a good reason not to bite off more than you can chew when it comes to car DIY. Small mistakes on relatively simple jobs (even something as minor as new headlights) can have significant consequences down the road and shorts can be quite difficult to find.
Normal Wear and Tear
As you drive, your car is constantly heating up, cooling down, vibrating, jostling, accelerating, and—well. You know what driving is like. All of that activity will eventually wear down your electrical system, introducing the potential for shorts.
As wires age, the material that insulates them (typically a PVC-like material, though actual insulation varies from car to car) cracks and deteriorates. As the coating sheds, the protection it provides begins to gradually deteriorate, introducing the potential for excessive heat build-up.
If you install new accessories, or in some other way tamper with the pre-set wiring, you may unintentionally introduce the conditions for electrical failure or strange quirks. When considering after-market products, it is always important to research what potential consequences could come from your alteration.
Electrical failure could also result from improper maintenance or simply a manufacturer’s defect. When the system goes bad, you may also notice flickering lights, blown fuses, sparks (always a solid reason to get your car looked at), and persistently poor battery functionality. If you experience any of these symptoms, it is important to contact your mechanic immediately.
2. The Key Interlock Solenoid (Especially For Short Drives)
What, you didn’t think of blaming the solenoid? While it sounds like something you might need to see a dermatologist about, the “solenoid,” is actually a fundamental feature—connecting your battery to the starter.
The solenoid will generate heat when activated, and that heat may still be observable to the touch—particularly after shorter drives.
Of course, this is a possibility for which the subjectivity of the word “hot,” comes into play. If your key feels up to the task of branding cattle, the solenoid probably was not to blame.
3. Ignition Switch
The ignition switch is the point of direct contact between your key and the rest of the car. Under normal circumstances, it will not overheat. However, if your ignition switch is failing, there may be conditions present that could result in a hotkey.
Usually, ignition switch failure will have other more obvious symptoms than just a hotkey. For example, if your car isn’t starting immediately when you turn the key into position, the ignition switch is a possible culprit.
However, if the ignition switch failure is electrical in origin, heat transference to the key can occur. Depending on the severity of the issue, you may also find that the plastic around the ignition has melted or distorted.
In this situation, it’s time to start a different field of research, such as “Will my car insurance cover a tow truck?”.
Don’t drive a car that is melting on the inside.
If you do want to further investigate the potential for ignition switch failure, here is a video that might help you better understand the issue:
4. You Could Have A Grounding Issue
Cars feature grounds that connect to the metal frame beneath the hood and sometimes these can malfunction. That connection helps regulate the flow of electricity. When a ground becomes loosened or otherwise compromised, the electric flow increases.
More electricity means more heat. See where this is going?
Usually, when your ground is compromised, a hot key won’t be the first thing you notice. Flickering lights, a failure to start, dimming headlights, and burning smells are all more common symptoms.
Still, it is certainly possible for the heat generated by a faulty ground to find its way to your key. And if you’re seeing other electrical issues along with a hot key, then you could have a grounding problem.
It’s Probably Not Moisture Infiltration
Moisture infiltration is not a probable culprit for the issue you are experiencing. We include it here on this list because it can technically play a role even. And just to be clear, moisture inside your car (like condensation on your windows) isn’t going to impact the temperature of your key.
If you’ve visited other websites covering this topic, you probably saw water listed as a reason behind hot key metal. Their reasoning is that if water comes in contact with the electric and metal elements present on your key and in the ignition, it will result in heat accumulation that may linger even after the key is removed.
If conditions conducive to your car getting moisture in its ignition have been met, this possibility may be worth exploring. However, that’s pretty unlikely because if moisture was the main issue, you’d likely experience additional symptoms such as difficulty turning the key, intermittent ignition failures, or even visible signs of corrosion on the key or inside the ignition.
In short, the conditions for this to be possible are very unlikely so while it could (in theory) happen, it’s not likely the cause of your hot car key.
Nope, Hybrids Are Not Overly Prone To Hot Keys
Hybrids often face skepticism on the internet, and there seems to be a misconception that they’re more prone to “hot key” issues than other vehicles.
Some suggest that because hybrids utilize a process called regenerative braking to economize fuel and recharge the battery, they generate more heat. While regenerative braking does produce some heat, it’s localized to the brakes and the battery system, and it’s very unlikely to influence the temperature of your car key.
When it comes to the hybrid’s engine, it produces heat just like any car, but this heat isn’t any more likely to impact your car’s key than any non-hybrid vehicle. So, while hybrids might be different in many ways, a hot key is not a common issue associated specifically with them.
Hondas Aren’t More Prone To Hot Keys Either
Honestly, I’ve dug deep for a real reason why Honda keeps coming up when it comes to hot car keys and I can’t find an explanation. The best I could come up with, is that the soy wires used by Honda could lead to more electrical problems and maybe hotter keys.
But so many other manufacturers use the same wiring that it just doesn’t hold up. You’ll find these wires in everything from a Camry to an Audi E-Tron and everything in between.
In short, there’s nothing in my training or years of experience that tells me Hondas are more likely to have hot car keys so this theory is a dud.
Don’t Forget To Consider The Condition Of Your Key
It’s important to note that the condition of your key should not have a significant impact on how it handles heat. We are, after all, talking about a pretty simple piece of equipment, for which modification potential is very limited.
But hey, we covered the scary stuff pretty exhaustively, so let’s play devil’s advocate. Say your car and the key that turns it on is older.
Both have been through the wringer. Exposed to moisture. Heat. Rust?
As the car keys composition changes, its performance will as well. Wear and tear can potentially change the way that your key retains heat, making it feel different to the touch than it used to.
Is A Hot Car Key Always A Big Problem?
A truly hot key is almost always a consequence of some underlying issue. However, the surface temperature of your car key may fluctuate based on certain conditions.
- Long drives. The longer you drive (or even idle) your car, the more heat the engine creates. Given enough time it is possible for some of that heat to make your car key feel a little warmer than usual.
- Hot weather. And of course, car interiors can get significantly hotter than even the outdoor temperature during a heat wave. If your key feels hotter than usual after driving in unusually high temperatures, it may be a byproduct of the outside temperature.
If you register a small temperature increase on your key surface when one of those conditions has been met, you may not need to take your car into the shop. However, it is important to keep a close eye on the situation. If the problem does turn out to be electrical, it should be fixed as quickly as possible for your own safety.
How Much Will Fixing My Hot Car Key Cost?
Yeah, that’s always the question, isn’t it? And like all automotive repair questions, it does not have an easy answer. If we are just talking about a loose connection, or maybe a simple splice, you may be looking at a (relatively) minor bill.
If it’s a total system failure, significant rewiring will be required. Depending on the complexity of your car’s electric system the repair could be thousands of dollars.
If it turns out other components have been damaged, the bill could be significantly more. Which leads to a natural follow-up question:
Can I Fix A Hot Car Key Issue Myself?
While changing a tire or checking the oil are relatively straightforward processes, diving into the electronics of your vehicle is significantly more complicated.
Wiring issues can have a domino effect and result in everything from a bad battery and accessory failure to poor engine performance and even air bag malfunctions That’s not even taking into account the computer hardware that most modern cars have.
It’s just not something that the average vehicle owner can handle on their own. It’s better to take the car in, pay the diagnostic fee, and see what the pros say. With a little luck, it might be a simpler fix than you were expecting.
While some temperature fluctuations might be harmless and due to external factors like long drives or hot weather, significant heat in your key often points to underlying electrical issues that require prompt attention.
Whether it’s wear and tear, damaged insulation, after-market modifications, or ignition switch problems, any sign of excessive heat is a warning signal that shouldn’t be ignored.
Remember, while the allure of DIY car repairs might seem cost-effective, electrical complexities are best left to professionals. The well-being of your vehicle and your safety is paramount. If your key is unusually hot, it’s usually a good idea to call a mechanic before the problem gets worse.
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
Read more about our fantastic team on our about page!