how can i check error 1651 for my iPad4

Hi, what are you trying to do? Update your iPad's OS?

You may need to ensure a SIM card is inserted into the iPad. Remove or switch the SIM card in your iPad - Apple Support. If you're using the iPad 4th Generation, you'll refer to the 3rd illustration down (at the time of this posting).

Check that airplane mode is off and Bluetooth is on. Use Airplane Mode on your iPhone, iPad, iPod touch, and Apple Watch - Apple Support.

If your device is functional, Please ensure that you have a recent backup. Back up iPad - Apple Support.

You may need to restart the device. Restart your iPad - Apple SupportOfficial Apple Support › en-us

It may also be a good idea to check your cables at this point. Make sure the cable you're using is in good working order. Test it with other devices if available and use different jacks to see if the cable works correctly.

Ensure that if you're using iTunes, it is up to date. Update to the latest version of iTunes - Apple Support.

If all looks good, try to update again. Depending on your system, either use: Update your iPhone, iPad, or iPod touch with the Finder - Apple Support or Update your iPhone, iPad, or iPod touch with iTunes - Apple Support.

Note: the above articles have instructions to update your computer system. Suppose you have windows updates available or Mac OS updates available. In that case, it is recommended that you install them and try again. If you're still having issues, follow: If you can't update or restore your iPad - Apple Support.

If these steps fail, you'll find additional links for: If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support. Step 4 of this article (at the time of this posting) may be the most challenging step to complete. Refer to: Resolve issues between iCloud for Windows or iTunes and third-party security software - Apple Support or contact the developer of any security apps that you believe may be interfering with the connection: How to contact an app developer - Apple Support.

And last but not least, contact Apple Support.