Toyota released a software update to fix a problem that caused the Check Engine Light to come on. Before the update, the computer would report a problem with the catalytic converter when there wasn't one.Google+
Car Problem Reports
Toyota RAV4 Software update to correct false catalytic converter failure
Toyota RAV4 Problem
Average Mileage: 141,250 mi (100,000 mi - 178,000 mi)
Visitor, 2001 Toyota RAV4, 172,000 mi
Had the catalytic converter replace, 5 months later check engine light again for catalytic converter failure and replaced it again.
Visitor, 2001 Toyota RAV4, 178,000 mi
Had my 2001 Toyota RAV catalytic converter replaced by a Toyota Dealership. Six years late at 178,000 miles I was told the cat converter had to be replaced. exactly 2 years later and at 192,890 miles, check engine light comes on and being told cat converter again.
If not updated light will come on about every 500 miles after being cleared