The generator matrix

 1  1  1  1  1  1  1  1  X  X  X  1 X^2 X^2 X^2  X  1  1
 0 X^3  0 X^3  0  0 X^3 X^3  0 X^3 X^3  0  0 X^3 X^3  0  0 X^3
 0  0 X^3 X^3  0 X^3 X^3  0 X^3 X^3  0  0 X^3 X^3  0  0 X^3 X^3

generates a code of length 18 over Z2[X]/(X^4) who´s minimum homogenous weight is 17.

Homogenous weight enumerator: w(x)=1x^0+12x^17+35x^18+8x^19+3x^20+4x^21+1x^22

The gray image is a linear code over GF(2) with n=144, k=6 and d=68.
This code was found by Heurico 1.16 in 0 seconds.