I am trying to replace the O2 sensor on my 2000 Avalon by the firewall (bank 1 sensor 1), and would like to know what procedures anyone has found that worked best. It does not seem to be covered in the Toyota manual - testing is, but I can't find a description of the best way to go at it.
I have an O2 socket but I cant seem to get at it. There are too many lines etc. in the way to get a rachet on it from underneath - I can't get am open end wrench on the O2 socket, but there isn't much leverage from the position.
It really looks like going from above and removing some of the intake (or the whole manifold) may be easiest in the long run. Anybody see this procedure posted somewhere?
The Following User Says Thank You to jur2 For This Useful Post:
Just replaced all three sensors on my daughter's 99 a few weeks ago, at appx. 130k.
Sprayed with PBlaster. Left for 10 min. Sprayed again and started working.
For B1 S1: Removed some of the air intake hoses for room to work, but didn't unbolt any hard parts. Protected fender, and leaned far in with O2S socket on a 1/2 in ratchet. Set ratchet about 30 degrees up from level, and left there to "dangle". Held appx. 2 ft. length of 1.25 in iron pipe vertical, resting on end of ratchet. (Not trying to slide onto ratchet; catch opening of pipe on the raised corner of the ratchet.) Hit top of pipe (I have a cap on it; could use block of wood) a few times with a 5 lb sledge. Once broken loose, the access is enough to routinely unscrew old and install new.
BTW, the post cat O2S was the worst. Broke the O2S socket on it. So, I removed the rear two exhaust sections as a unit (the center nuts and bolts were only there for 2 years, and actually came apart)...easy as it doesn't go up and over any axle/suspension.... I heated socket with propane torch, and used mallet with a box end wrench.
Total time for all 3 sensors was about 90 min, with an assist on the post cat sensor.
Just replaced all three sensors on my daughter's 99 a few weeks ago, at appx. 130k.
Sprayed with PBlaster. Left for 10 min. Sprayed again and started working.
Removed some of the air intake hoses for room to work, but didn't unbolt any hard parts. Protected fender, and leaned far in with O2S socket on a 1/2 in ratchet. Set ratchet about 30 degrees up from level, and left there to "dangle". Put appx. 2 ft. length of 1.25 in iron pipe straight down onto end of ratchet. (Not trying to slide onto ratchet; catch opening of pipe on the raised corner of the ratchet.) Hit top of pipe (I have a cap on it; could use block of wood) a few times with a 5 lb sledge. Once broken loose, the access is enough to routinely unscrew old and install new.
BTW, the post cat O2S was the worst. Broke the O2S socket on it. So, I removed the rear two exhaust sections as a unit (the center nuts and bolts were only there for 2 years, and actually came apart)...easy as it doesn't go up and over any axle/suspension.... I heated socket with propane torch, and used mallet with a box end wrench.
Total time for all 3 sensors was about 90 min, with an assist on the post cat sensor.
TedL; thks for the tips. Sounds like some brute force is needed to unseat these. I was hoping the Bank 2 sensor on the post would be easy since it is right up front. When you say removed intake hoses, was that pretty much all of them? Seems like that is the only way to get enough room to get my hand down the back of the engine to reach the O2 sensor.
Intake hose(s) = big hose(s) between TB and air cleaner box. I did a gen 1 with a single hose, yours is a gen 2. My gen 2 has dual hoses to dual TBs. Adapt to your specific situation. I was leaning/crawling in from the driver's side (US).
I am not petite, and neither are my hands/arms. If I can "get in" there, most people smaller than an offensive lineman can.
Spray with whatever penatrating stuff you like, cram arm and 22mm wrench in there, break sensor loose. Unplug, screw out sensor, reverse process to install. No need to remove any parts. Tip: place wrench on sensor, place something (board,long 1/2" drive extension) on end of wrench and strike with hammer to break sensor loose. Trying to unplug and plug in sensor with one hand is a challange.
just wanted to report that i took TedL's advice and changed both sensors (bank1 and bank 2). Started spraying liquid wrench on both for a few days while car was hot for penetration (do outside since some of the liquid will evap). I rigged a plastic line on a stick that allowed me to spray into the line and position it over the back sensor where it bolted into engine.
I did have to remove the two air intake hoses for room to work, but didn't unbolt any hard parts. Protected fender, and leaned far in over the engine with O2S socket on a 1/2 in ratchet. Set ratchet about 30 degrees up from level, and used a piece of pipe fitted over wrench that extended my reach and easily broke loose the sensor. The access was just enough to unscrew old and install new sensor but hardest part was getting the connectors to hook up. Need to make sure that prongs on connectors are aligned before u install to make sure they line up. Will now work on the 3rd sensor behind the cat since this one needs replacement as well. If anyone has done this and has a god technique, please advise
Remove passenger seat and pass door trim that overlaps carpet for access to connector. Reach in under carpet. If ND sensor, ck cable length to get location idea.
Try Pblaster a couple times. Then try a wrench with the limited access. Two ramps used on F&R pass side may give enough access for cheater bar.
Else, remove exhaust behind cat as a unit. Have new bolts, nuts , gaskets for center connection. Use torch (propane, MAPP, acetylene) to heat socket before trying to wrench off.
The Following User Says Thank You to TedL For This Useful Post:
The cost of these sensors is quite pricey as I too just changed all three sensors on my 2000 avalon (155k miles). Local Toyota dealer wanted $368 to change the b1s1 alone. I bought all three at Advance Auto Parts and changed them myself for less than $350. There is a web site (www.retailmenot.com) where you can get online shopping discount codes. There is currently a code on there for $50 off a $150 dollar order. I bought each sensor on seperate orders and selected to pick up at my local store, in case you haven't purchased them yet.
As far as time, I had a little over 4 hours with the b1s2 being the most time consuming with the seat removal. For the b1s1 i couldn't get at it either so I went to my local walmart and purchased a rachet with a rotating head and extending handle ($25) and had it out in minutes.
The 3 for my daughter's were $260. Denso OE part numbers. Her fuel mileage has increased by around 15%. This does not surprise me, as the fuel trim has been reduced greatly, now down close to zero %. From age, AFR sensors tend to fail in a way that gives a false lean reading, from what I've read.
just wanted to report to those following this thread that I changed the 3rd O2 sensor (post CAT converter) following procedure described by TedL in previous posting and it went smooth but i did start spraying sensor connection at exhaust pipe nipple a few days before with PB blaster (used small dia plastic tube on a dowel stick to get liquid onto O2 sensor connection with exhaust) . Jacked up passenger side front and rear to get enough room to work, getting the ratchet and sensor socket over sensor was not easy, Recommend buying smaller socket with side attachment for ratchet (Autozone sells them) to provide room for unbolting. Also, i had P codes indicating bad CAT but this was caused by bad sensor. After replacement, disconnected POS battery terminal to clear P codes and have gotten no more warning lights.
just wanted to report to those following this thread that I changed the 3rd O2 sensor (post CAT converter) following procedure described by TedL in previous posting and it went smooth but i did start spraying sensor connection at exhaust pipe nipple a few days before with PB blaster (used small dia plastic tube on a dowel stick to get liquid onto O2 sensor connection with exhaust) . Jacked up passenger side front and rear to get enough room to work, getting the ratchet and sensor socket over sensor was not easy, Recommend buying smaller socket with side attachment for ratchet (Autozone sells them) to provide room for unbolting. Also, i had P codes indicating bad CAT but this was caused by bad sensor. After replacement, disconnected POS battery terminal to clear P codes and have gotten no more warning lights.
We like success stories! Good work!
Spraying for several days is a good idea that I try to practice, but rarely remember to write. Good addition.
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