P1421 Nissan - failed emissions test MD diagnostic trouble code of P1421 KOEO/MIL Command failed

Question

What does this mean and how much to fix

Answer 1

see service bulletin on link below

https://www.autocodes.com/p1421_nissan.html

https://www.autocodes.com/uploads/nissan/NTB09-116.pdf

 

The computer needs to be updated this is done by dealer only, they will charge about one hour ($150 or so at least here in California)