The generator matrix

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

generates a code of length 4 over F9[X]/(X^2) who´s minimum homogenous weight is 18.

Homogenous weight enumerator: w(x)=1x^0+48x^18+2592x^24+224x^27+34992x^32+20736x^33+456x^36

The gray image is a linear code over GF(9) with n=36, k=5 and d=18.
This code was found by Heurico 1.16 in 0.00694 seconds.