The generator matrix

 1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1  1
 0  X  0  X a*X a*X a^2*X a^5*X  0  X a*X 2*X a^2*X 2*X a^2*X a^3*X 2*X  0
 0  0  X a^7*X a*X a^2*X a^6*X a^7*X a^3*X a^6*X 2*X a*X 2*X a^2*X  0  0 a^7*X a*X

generates a code of length 18 over F9[X]/(X^2) who´s minimum homogenous weight is 126.

Homogenous weight enumerator: w(x)=1x^0+48x^126+240x^135+6048x^144+96x^153+128x^162

The gray image is a linear code over GF(9) with n=162, k=4 and d=126.
This code was found by Heurico 1.16 in 0.00459 seconds.