I know similar questions have been asked but I'm specifically looking for the most cost efficient way to solve the following problem. I have a 2006 Lexus RX400h for which the physical door key does not fit the lock cylinder of the door (but it does start the car). I open the car door with the key fob. I bought the car this way so I don't know the exact backstory.

The fact that my physical car key does not open the door lock cylinder does not usually bother me. But when the battery dies, I am unable to get into my own car. So I'd like to resolve this situation. After speaking with some folks, I believe the previous owners probably changed the ignition cylinder without changing the door locks. Then they just reprogrammed the key fob to open the door and to start the car.

My current thinking is the following: It seems like changing the door lock cylinder is probably more expensive than changing the ignition cylinder back to factory specs and then getting a factory key and program that key to open and start the car.

I could get all of this done with my local Lexus dealership. But knowing dealerships, I am certain that this will be expensive. I also feel like I cannot get reliable information from the dealership, a mechanic, or a locksmith because all of them have an interest in selling me their services.

So now my question is what would be the least expensive way to deal with this?

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    What I did for my daughter with the same situation (09 Honda Fit - Door was replaced without the original lock getting placed ... there's a question on here about it somewhere), was to hook heavy gauge wires directly to her battery with two weatherproof posts inside the wheel well on the driver's side. If the battery in the car goes dead, she can hook a small 12v source up to the posts and get enough juice to unlock the door and thus the hood to give the car a boost. Commented Aug 26, 2020 at 0:09
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    Frame challenge: Buy a decent battery that doesn't keep going dead / Stop leaving your lights on.
    – Valorum
    Commented Aug 26, 2020 at 8:12
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    @Valorum The battery dying in a car is a failure state. The battery dying in the fob is expected. Read as a native, he's not talking about his car battery. I don't know of a single person who sellotapes CR2032s to their car. Commented Aug 26, 2020 at 16:26
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    @Pᴀᴜʟsᴛᴇʀ2 I'm curious why heavy gauge wires as a permanent fixture when the 12v source is "small" - was the intention that the car could be boosted via the wheel well?
    – Caius Jard
    Commented Aug 26, 2020 at 16:41
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    @CaiusJard - When I say "heavy gauge" wires, I'm suggesting something like a 14-16 gauge on each the + and - leads. The idea is to give the car enough juice to open the locks via the fob versus using it to boost the car and start it. I wouldn't use something like a 22 gauge wire or the like. I'm just suggesting something which is a little heavier so you don't have any issues. And by "small", I'm talking something like a 12vdc battery you'd find in a battery backup (UPS) or used for a garage door opener. It's much bigger than a D-cell, but quite a bit smaller than a car battery. Commented Aug 26, 2020 at 17:19

2 Answers 2


Being a auto locksmith, I can 100% recommend that you have your door lock rekeyed to match your current ignition key. Cost will depend on location and if you remove the the lock yourself and take it to a shop or if you call a reputable mobile smith to come out. I charge about $90 for mobile service and a simple rekey like this.

The lock is simple to remove, there is a set screw on the side of door frame you undo and the lock pulls out to remove. I guess a shop would charge about $50.

Rekeying ignition is not as easy because these are somewhat sealed units and need a little drilling to open up so it will cost more. I'd say more along the lines of $100 shop/ $200 mobile. PLUS you will need to have a new case cut to move transponder in or new key programmed all together to match back to the ignition which will be in addition to the ignition rekey cost.

Dealer has no idea how to rekey anything. They will just replace stuff. I wouldn't bother with them in this case.

Its also possible your door lock is just seized up. It is very common on lexus locks around those years. Bad grease that dries up. Spray a healthy bit of wd40 in there and work your key in and out some. If still does not work take the lock out and spray MORE wd40 in the big drain hole underneath the lock while putting your key in and out.

  • Are your prices linked to your location or valid across the world?
    – Solar Mike
    Commented Aug 26, 2020 at 4:12
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    Its about the norm for my region and likely close all around the US. But it will vary depending on location. As for the question itself, The cheapest way to achieve what they are asking will be to rekey the door lock regardless or location.
    – narkeleptk
    Commented Aug 26, 2020 at 4:40
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    "Its also possible your door lock is just seized up." I second that.
    – fraxinus
    Commented Aug 26, 2020 at 13:27
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    I wholeheartedly agree with this. Ignition hard, door easy. Just remove the door lock and walk it into a retail locksmith. Commented Aug 26, 2020 at 20:53
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    Having replaced several door locks in my lifetime do to botched thefts etc, My first instinct as well was that getting a new door lock would be much easier than a new ignition. Commented Aug 27, 2020 at 17:47

Your cheapest option might be to leave everything keyed the way that it is and simply have separate keys for the door and for the ignition. You'd have to get a key made for the door, but that should be cheaper than rekeying the lock. This is what I do with my house, which has two different locks on different doors. One of those keys only gets used on very rare occasions, similar to OP's situation, so it's not a lot of extra hassle. However, this option would get extremely annoying if this was your primary way of unlocking the door.

  • This is another option, yes. Still, my charge would be the same or cheaper for a rekey vrs a (all keys lost) replacement key on this one. Its basically a simple service call/flat price to cover the time for 1 basic job on this particular keyway either way you look at it. Most walk-in shops are going to be the same as me just without a extra charge for coming too you. You may give a smith the keycode from the door lock and sweet talk them a bit to get a discount on a basic "code cut key" but I wouldn't count on it being much cheaper on this key system.
    – narkeleptk
    Commented Aug 27, 2020 at 0:26

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