This instruction guide applies to older versions of Bob PetHair (prior to 2016).
Dark colored carpets or certain patterns can seem like an edge to Bob's infrared sensors. If Bob displays Error 4 (Trouble Nr 4 for PetHair), you can "blindfold" Bob by covering the 4 small floor detection sensors underneath him. Make sure Bob is not getting anywhere near stairs or sharp edges when blindfolded or he can fall.