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Posts: 45
Registered: ‎09-07-2016
Location: US
Views: 670
Message 1 of 1

x1 yoga WWAN SIM card occasionally not detected

I have an x1 yoga WWAN where SIM card occasionally not detected. This can even happen in the middle of an active LTE connection. Reseating the SIM helps but even without reseating if I run an AT!RESET to reset the EM7455 wwan card, it will start working again. I have not done any troubleshooting but would like to know what the most likely failure mode is:

- Bad EM7455 card

- Bad sim slot with a glitchy contact

- bad solder job or other connection issue between EM7455 M.2 slot and SIM slot.


I.e. how likely is it that replacing the EM7455 will resolve this? One other poster on this board had Lenovo come out and replace the entire motherboard but that seems drastic in my case as it works fine 95% of the time.

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