Problems with Deskjet Plus 4120

[Jos64]

I am at a complete loss. I just can't manage to connect my printer with my wi-fi. I tried so many things and nothing worked

and now i am totally confused. 

I have a Deskjet Plus 4120 printer, thats at least one or two years old. In all that time we never managed to connect it to wifi. I started another try today. I installed the HP app on my android and i also have HP Smart on my pc. Everytime i connect the printer to my pc  via a cable HP smart says my printer is offline. I cant go to expanded settings to connect the printer to wireless because its grey and i can't click it. When i try to do the setup on my phone , the app doesn't find my printer. I tried to update the software but HP Easy start also can't find my printer. 

I dont know if the printer was ever set up with wifi but we also have a new wifi and router so i need to set up everything again. 

Also the printer doesn't recognize a cartridge and i can't delete the error ( Error 0! the color cartridge is empty). 

Please , i just wanted to print something. Can somebody help me ? The virtual assistant only suggests the same methods that didn't work before. I tried to go via the wifi setting on my pc and connect to the printer the same way i would connect my  pc to my wifi, and the printer wanted a PIN. I tried the PIN that i found on a sticker inside my printer but it wasn't the right one. 

[Kuroi_Kenshi]

Hi @Jos64,

Welcome to the HP Support Community!

Thanks for reaching out!

We're thrilled to have the opportunity to assist you and provide a solution.

I understand your HP DeskJet Plus 4120 isn’t connecting to Wi-Fi, shows an offline status, and is reporting a cartridge error. Let’s go step by step to get it working. I’ll keep it simple.

1. Power Cycle Everything

Turn off the printer, unplug it for 60 seconds, then plug it back in and turn it on.

Restart your router and your computer/phone.

2. Reset the Printer’s Network Settings

On the printer, press and hold the Wireless button (or the Cancel button depending on model) for 5–10 seconds until lights blink.

This clears old Wi-Fi settings so you can start fresh.

3. Connect via HP Smart App (Phone or PC)

Open the HP Smart app on your phone or PC.

Tap Add Printer → Set up a New Printer.

The app should detect your printer. If it doesn’t, choose Printer Not Found → Wireless Setup.

Make sure your phone or PC is on the same Wi-Fi network you want the printer to use.

4. Use WPS (if router supports it)

Press the Wireless button on the printer until it starts blinking.

On your router, press the WPS button within 2 minutes.

The printer should connect automatically.

5. Cartridge Error (Error 0)

Open the printer cover, remove the color cartridge, and check for:

Protective tape still on the cartridge

Dust or debris on the cartridge contacts

Reinsert the cartridge firmly until it clicks.

If the error persists, try replacing the cartridge with a new genuine HP cartridge.

6. USB Temporary Connection

If Wi-Fi setup still fails, connect the printer to your PC with a USB cable.

Open HP Smart → Add Printer → USB Connection.

Once recognized, you can try setting up Wi-Fi from the app again while the printer is connected.

I hope this helps.

I'm glad I could help! 😊 If this resolved your issue, please mark it as "Accepted Solution" and click "Yes" on "Was this reply helpful?" Your feedback not only keeps us going but also helps others find the solution faster! 👍✨

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Best regards,