Review on Denso 234 9002 Fuel Ratio Sensor by Lawrence George

My 2001 4Runner VSC and check engine lights came on at about 130,000 miles pulling the code and of course the infamous air/fuel sensor code P1135. Some internet research revealed it was a simple DIY job, requiring 12mm and 10mm wrenches and about 30 minutes of my time. As I have a dual catalytic converter emissions model it required replacing the front sensor which is an air/fuel sensor rather than the less expensive O2 sensor. Apparently, models with a catalytic converter have an O2 sensor at this point. You can go underneath and look at the exhaust, look for little muffler like things in the exhaust pipe and if you have two then you need this air/fuel sensor to solve the P1135 problem. The sensor is located at the top of the exhaust pipe where it is angled toward the engine, towards the front of the vehicle (passenger side). It was pretty easy to find by just crawling under the 4Runner behind the passenger bike. This Denso brand appears to be original equipment for Toyota and is a recommended replacement. Shipping took a little longer than standard 2 day prime but still arrived quickly and the price was great. The product turned out to be identical to the original. My sensor screws were in perfect condition with no corrosion so I didn't bother replacing them as some people are suggesting. I just sprayed some liquid wrench on it and let it sit for about 30 minutes and the 12mm bolts came right off. Remove the 10mm screw from the harness bracket so you can lower the connector for easier pressing on the tab and disconnect. Clean the flange, put in a new gasket and sensor and retighten the bolts. Insert and reconnect the connector. Disconnect the battery for a few minutes or use a code reader to reset the code. Spend 30 minutes under a car and save $200.