Not come across this myself but I assume you are reading the code from the amber service indicator to the lower left of the spanner light? If this is the case, the code is a two followed by a 58, not 258. The 2 indicates an EXEC ERROR according to the manual but doesn't list any codes other than 81 & 82 which are steering module related. Check the Access 3 and steering modules when the code is displayed on the display module and see if either is also flashing a code, this should help narrow it down. I would suspect its a communication error between the modules, either an overmast cable or at the distribution board. Failing that it could be a module failure, swapping with another machine would be the best course of action if you have a second identical machine on site. Check the manual under 'Service LEDS' in the Display & Steering Modules section for a little more info.