The generator matrix

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

generates a code of length 21 over Z4[X]/(X^2+2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+43x^18+342x^19+391x^20+534x^21+385x^22+284x^23+38x^24+14x^25+4x^26+10x^27+2x^32

The gray image is a code over GF(2) with n=168, k=11 and d=72.
This code was found by Heurico 1.16 in 0.015 seconds.