Is there a way to fix an error with code 4B

Hi. I have a Nuki Smart lock 2 from 3 years and recently the motor stoped to work. I tried to make the calibration as I read here in this blog but the Nuki app returned the error code 4B. In the activity log the error code is 0x07. I contacted with the support and they told me that the lock is completely finished.
I would like to know if there is a way to fix the motor issues? Or is it possible to change the motor itself?
I bought a new smart lock already but would like to know if there is any chance to bring this lock back to life.

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Hi! Was it new? Because when have to buy all three years new locks, would be a big boo!? Thanks!

Yes. Unfortunately it was new Smart lock, but finished his life on the 3th year. It will be not fair if the customers will be not able to fix some of the problems. If I have to buy a new lock every 3 years I would like to be because of something new and better in the technology or in the design or something like that. Not because the previous one is broken.

Same for me 3 years and finished error 4B . It seems to be a common default :frowning: it’s a shame ! And also the 3.0pro is not available in stock !! I will look for an other brand maybe .

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Big downer is this👎!

Hi there, had the same problem 2 time. After 1 year and solved as warranty case and now again after 2 years, out of warranty. So tried to get one under goodwill but without success. So i tried to fix the problem by myself and what shout is say? It was only a loose wire on the gear lock motor which i have welded and it work fine again. :slight_smile:


Very cool, thanks for sharing! Was it hard to get inside the lock?

Hi ,

It’s the same for me but now that I dismount it , I would like to remount it and I can pout in place all the gear except one , that fall down when I open the lock . Could you give a hint on how to place back all the wheel correctly ?


no, its onyl one screw and then remove the cover plate. After that you can see and check the wiring.

Cant help in this case cause i only removed the cover plate to get on the wires. It was not necessary to dismantle the whole unit.
But i found this: A peek inside the Nuki Smart Lock - The π Computer Club
Maybe that whould help to assemble.


Hello, Sometimes there is a was to fix this. Here on a Nuki 2.

There are 2 Motors in the Nuki Lock (Both by the way around 5€ on eBay, just search for what is written on them).
The first one powers the lock, this is the one you see when you remove the back cover.
The second motor seems to switch between “the wheel can be turned by hand / key freely” and “knob is moved by motor with the gears ( then it is harder to turn)”. this one has one gear wheel (looks like a halved one) that had jumped out as it seems . I am not exactly sure but after dismantling the gearshift and reassembling it, it worked fine again.

My only fear is the gear wheel could be worn out (all plastic), then the defect will happen again soon. Did not find a replacement.

Other things You can check :

-Cables to both Motors (red/ black, yellow, blue?) (very thin, pay attention)
-the motors themselves. Just use an external 3-5 volt power supply.

Hope this helps! So in some cases, there’s no need to buy a new lock.

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Hello, I had the same problem with error code 4B. First, I checked wires both motors. Desoldered wires from the board. Both of them were OK. Then I found magnetic sensor on glass tube close to battery pins. I desoldered it from the board. Problem was SOLD OUT! I think if the glass component is wrong it could give fake info that door is closed.

Thank you Martin for the info. I will try to do the same and will see what happen.

WARNING: This part has nothing to do with error 4b and removing it will destroy other functionalities of the Smart Lock (e.g. it won’t detect manual unlocking with a key anymore, loose control over it’s position etc.).

Most likely you did move around some cables while dis- & reassembling the Smart Lock, which might have solved 4b for you.

This is a great Video for Nuki Repair

One quick question to this topic (sorry to reactivate after some months!)
When the clutch is blocked and the motor will only turn very hardly … is it still possible to force the motor from the outside with a Key? Or is it strong enough to cause that the key will before get broken?
Are you inevitably locked out of home?!