O2 sensors failed due to rodents or rabbits chewing the plastic wiring housing the internal electrical wires. O2 sensors had to be replaced at a cost of about $600. The outside coatings or sheaths for the wiring is made of a soy based plastic, and possibly containing a "fish oil" in the sheath, which attracts rodents and rabbits, and they chew on the plastic wire coverings, thereby destroying the O2 sensor's wiring mechanism. This problem is prevalent in the denver and mountain states areas and should be corrected as the problem could lead to engine fires or engine failures. The wiring housing should be changed to a "retardant" type of wiring to prevent other incidents of this problem, and not just for Toyota but for all manufacturers.

- Golden, CO, USA