The generator matrix

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

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+96x^18+32x^19+114x^20+576x^21+90x^22+32x^23+54x^24+20x^26+6x^28+2x^30+1x^32

The gray image is a code over GF(2) with n=168, k=10 and d=72.
This code was found by Heurico 1.16 in 48.3 seconds.