The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  X  X  X  1  X  1  X  1  X  X  X  1  1  1
 0  X  0  X (a+1)X (a+1)X  0  X (a+1)X  0  X (a+1)X aX aX aX aX  0  0  X  X  0  X aX aX aX  X  X  0  0  X  X aX aX aX aX (a+1)X (a+1)X (a+1)X (a+1)X
 0  0  X (a+1)X (a+1)X  X aX aX  0 (a+1)X  X aX  0  X aX (a+1)X  0  X (a+1)X aX aX  X  0  X (a+1)X aX  X  X (a+1)X  0  0  X aX aX  0 aX (a+1)X aX  X

generates a code of length 39 over F4[X,sigma]/(X^2) who´s minimum homogenous weight is 113.

Homogenous weight enumerator: w(x)=1x^0+84x^113+27x^116+48x^117+27x^120+36x^121+9x^124+24x^125

The gray image is a linear code over GF(4) with n=156, k=4 and d=113.
This code was found by Heurico 1.16 in 0.016 seconds.