The generator matrix

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

generates a code of length 18 over Z2[X]/(X^4) who´s minimum homogenous weight is 12.

Homogenous weight enumerator: w(x)=1x^0+150x^12+686x^13+3034x^14+10336x^15+27257x^16+54486x^17+70000x^18+54672x^19+27646x^20+10138x^21+2826x^22+720x^23+146x^24+34x^25+12x^26

The gray image is a linear code over GF(2) with n=144, k=18 and d=48.
This code was found by Heurico 1.16 in 85.2 seconds.