The generator matrix

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

generates a code of length 9 over Z4 who´s minimum homogenous weight is 6.

Homogenous weight enumerator: w(x)=1x^0+6x^6+9x^8+32x^9+9x^10+6x^12+1x^18

The gray image is a code over GF(2) with n=18, k=6 and d=6.
This code was found by Heurico 1.16 in 0.000246 seconds.