For large-size buses, the electrical wiring in the engine compartment is not properly routed, and therefore, it may interfere with the bolts that secure the muffler. If this problem is left unattended, the wire sheath may be damaged due to vehicle body vibration etc. If a short circuit occurs, in the worst case, the lights on the rear, such as brake lights, could fail, or the engine could stall and would not restart.