The generator matrix

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

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

Homogenous weight enumerator: w(x)=1x^0+11x^18+28x^19+52x^20+336x^21+52x^22+12x^23+10x^24+8x^25+1x^26+1x^40

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 0.016 seconds.