Where are the oxygen sensors on a Toyota Avalon?

Answer 1

O2 sensorsThere are actually (4) four oxygen sensors. One in front (closest to radiator) exhaust pipe, one in rear (closest to firewall) exhaust pipe, one at the cataylitic converter and one at the resonator. I have had direct experience with the two in the engine compartment but have not had the pleasure of working on the other two. I can say that it is much cheaper to buy a good quality part like Boosch (about $50) to replace the OEM part although the OEM or Toyota part is easier to install. The aftermarket parts are good quality but the wiring can be a little tricky. Also, make sure your diagnosis is acurate. You want to make sure you replace only the faulty one. I had my wifes Avalon diagnosed at a Toyota dealer for free and was told that it was sensor bank number 2, which is the one near the firewall. You can disconnect the negative battery cable from the battery for a minute or two then reconnect and drive your vehicle. This will sometimes fix "soft" code problems. If the Check Engine light comes back on after a period then it is a "hard" code and further diagnosis is in order. You can also remove the suspected bad sensor and clean it with compressed air and a soft brass bristle wire brush to remove accumulated carbon and deposits. I also recommend a good "anti-seize" compound on the threads when reinstalling your sensors so they will be more easily removed next time. I am not a professional mechanic but I do have over 30 years of experience maintaining my personal vehicles and although my advice is good, my recommendation is to take it to a qualified shop for diagnosis and repair..