The generator matrix

 1  0  1  1  1  0  1  1  2  1  1  2  2  2  2  0  2  1  1  0
 0  1  1  0  3  1  2  3  1  2  1  1  0  0  2  2  0  0  3  1
 0  0  2  0  2  0  0  2  0  0  2  0  2  2  2  2  0  2  0  2
 0  0  0  2  2  2  2  0  2  0  2  0  2  0  0  2  0  2  0  0

generates a code of length 20 over Z4 who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+22x^18+22x^20+10x^22+8x^24+1x^32

The gray image is a code over GF(2) with n=40, k=6 and d=18.
This code was found by Heurico 1.16 in 0.0011 seconds.