The generator matrix

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

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+153x^18+192x^19+486x^20+384x^21+486x^22+192x^23+153x^24+1x^42

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 0.078 seconds.