The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  2
 0  2  0  0  0  2  2  2  0  0  0  2  0  2  2  2  0  0  0  2  2
 0  0  2  0  2  2  2  0  0  0  2  2  2  2  0  0  0  0  2  2  0
 0  0  0  2  2  0  2  2  0  2  2  0  0  2  2  0  0  2  2  0  0

generates a code of length 21 over Z4 who´s minimum homogenous weight is 20.

Homogenous weight enumerator: w(x)=1x^0+18x^20+8x^22+4x^24+1x^40

The gray image is a code over GF(2) with n=42, k=5 and d=20.
This code was found by Heurico 1.16 in 0.00126 seconds.