The generator matrix

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

generates a code of length 21 over Z4 who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+264x^12+1008x^14+2529x^16+5130x^18+7631x^20+7008x^22+5438x^24+2532x^26+998x^28+192x^30+32x^32+2x^34+3x^36

The gray image is a code over GF(2) with n=42, k=15 and d=12.
This code was found by Heurico 1.16 in 12.4 seconds.