The generator matrix

 1  1  1  1  1  1
 0  X  0  0  0  X
 0  0  X  0  0 a^7*X
 0  0  0  X  0 a^7*X
 0  0  0  0  X a^6*X

generates a code of length 6 over F9[X]/(X^2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+120x^18+1120x^27+6840x^36+21840x^45+472392x^48+29128x^54

The gray image is a linear code over GF(9) with n=54, k=6 and d=18.
This code was found by Heurico 1.16 in 1.37 seconds.