I have a T410 with the intel 6200 wifi card.
My buddy has a T420s with just the thinkpad wifi 1x1 card.
I thought i would try my 6200 card in his laptop to show him the diffrence in a good wifi card.
But after installing the 6200 in his T420 he gets the 1802 error.

I always thought the T410 and T420 cards could work in eather.

My buddy needs to get a good wifi 6200 or 6300 card for his T420s.
Ebay shows alot of listings for the 6300 for the T410 and T420's for the same card.

Giday Bill;
lovely part of this earth u live in <jelious>.....
T420s = strange strange animal ,, having had a few of them in past ( work ones)
and I also happen to think of simailar ways , wanted to move my T410 (gobi cards + wifi+wimax cards to T420s ,,,, I found the hard way - Lenovo MADE MAJOR changes to their BIOS to STOP PPLE from DOING that (via a BIOS update)

There are few workarounds etc , but in-short , be cheaper (better) to jsut spend the 125$US
Fyi - goggles 1802 error thinkpads

Cheers