P0156 error Pathfinder O2 sensor repair

[mlang]

I am having the rear left bank O2 sensor in my '96 Pathfinder replaced. However, is it really necessary to have the sub-harness between the intake manifold and the cylinder header (to provide a direct path to the ground) replaced? Service bulletin only suggests this harness be replaced. At what point should the subharness installed? I do not want to spend the additional money if it really does not need to be done. Thanks.