The generator matrix

 1  1  1  1  1  1  1  1  X  X  1  1  X  X  1  1  1  2  1  X  X
 0  X  0  X 2X  0 X+2 3X+2  2  X 2X+2  0 3X+2 3X+2 2X+2 3X 2X  X 3X+2  0 3X
 0  0  X  X  0 3X+2 X+2 2X  X X+2 3X 2X+2  2 2X 3X+2  0 X+2 2X+2 3X+2 2X+2 3X+2
 0  0  0  2 2X+2  2 2X  2  0  2 2X+2 2X  0 2X+2 2X+2 2X+2 2X  0  2  2  0

generates a code of length 21 over Z4[X]/(X^2+2) who´s minimum homogenous weight is 17.

Homogenous weight enumerator: w(x)=1x^0+100x^17+258x^18+456x^19+657x^20+1224x^21+652x^22+400x^23+167x^24+116x^25+50x^26+8x^27+7x^28

The gray image is a code over GF(2) with n=168, k=12 and d=68.
This code was found by Heurico 1.16 in 0.078 seconds.