The generator matrix

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

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+25x^18+16x^19+49x^20+352x^21+26x^22+16x^23+13x^24+13x^26+1x^36

The gray image is a code over GF(2) with n=168, k=9 and d=72.
This code was found by Heurico 1.16 in -6.48e-008 seconds.