In November, it was discovered that Google's Nexus 4 had a LTE chip in it. Some users were able to get the 3G-only phone onto 4G LTE networks in Canada, but it wasn't exactly a widespread exploit. It apparently was enough of an issue, however, for Google to patch it out in the latest Android update.
Anandtech reports that the latest Android update hitting the Nexus 4 - Android 4.2.2 - has removed the ability for the Nexus 4 to access LTE networks on band 4. Before, users could simply access LTE by choosing band 4 under Phone Info. That method of connecting to LTE has now been removed, and it doesn't look like there's any other way to access it.
Here's the guys from Anandtech showing how the Nexus 4 automatically kicks users off of LTE after the update:
It's an unfortunate turn of events for those who were getting LTE speeds on such a cheap phone, but it really was only a matter of time before Google patched it out. If you still want to get access to LTE, Droid Life suggests users either wait on updating or hope an enterprising developer takes out the radio update from the latest Android update.
Either way, Nexus 4 owners will probably find a way around this latest update to keep getting their LTE speeds.