The generator matrix

 1  0  1  1  1  1  1  1  1  0  1  1  1  1  0  1  1  1  1  2  1  1  1  1  2  1  1  2  1  1  1  1  1  1  1  1  1  1  1  1  1  1  2 2a+2  1  1  1  1
 0  1  1  a a+1  0 2a+3  a a+1  1  0  a 2a+3 a+1  1  2 2a+3 a+2 a+3  1  2  1 a+2 a+3  1  2 2a+1  1 a+2 3a+3 2a+3 2a+1  3  0 2a a+3 3a+3 3a+3  2  1 a+3 2a 2a+2  1 2a+1 2a 3a+3  a
 0  0 2a+2  0  2  0  2 2a 2a 2a 2a  2 2a+2 2a+2  0 2a+2  0 2a+2  0  2  2 2a 2a  2 2a+2 2a  2 2a 2a+2 2a  0 2a+2 2a+2 2a  2 2a 2a+2 2a+2  2 2a  2  2 2a+2 2a+2  0  0 2a+2 2a
 0  0  0  2 2a 2a  0 2a  2  2  0  2 2a  2  2  0  0  2  2  2  0  0  2  2  2 2a 2a  0 2a 2a 2a 2a+2  2  2 2a+2 2a+2  0 2a  2 2a+2 2a+2 2a 2a  0 2a+2 2a+2 2a+2 2a+2

generates a code of length 48 over GR(16,4) who´s minimum homogenous weight is 136.

Homogenous weight enumerator: w(x)=1x^0+660x^136+1020x^140+966x^144+747x^148+525x^152+150x^156+15x^160+3x^164+9x^168

The gray image is a code over GF(4) with n=192, k=6 and d=136.
This code was found by Heurico 1.16 in 0.0811 seconds.