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 X^3+X^2  0 X^2  0 X^3 X^3+X^2 X^3+X^2  0 X^2 X^2 X^3 X^2 X^3  0 X^3+X^2 X^3 X^2  0 X^3  0
 0  0 X^3+X^2 X^2  0 X^2 X^2 X^3 X^3 X^2 X^3 X^3 X^3+X^2 X^2 X^3+X^2 X^3 X^3+X^2 X^3 X^2 X^2 X^2
 0  0  0 X^3 X^3 X^3  0 X^3 X^3  0  0  0 X^3  0 X^3  0 X^3 X^3 X^3 X^3  0

generates a code of length 21 over Z2[X]/(X^4) 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 linear code over GF(2) with n=168, k=9 and d=72.
This code was found by Heurico 1.16 in 0.015 seconds.