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Which Oxygen sensor is bank 2?


clampjockey
08-13-2008, 10:29 AM
i have a 96 camry 4cyl, shoots trouble code 0172 "system to rich bank2". i assume its an O2 sensor but which one is bank 2? the top one or the bottom? thank you.

Mike Gerber
08-13-2008, 03:19 PM
I'm a little confused here. A 4 cylinder 5SFE engine only has one bank with 2 O2 sensors. A V6 engine would have two banks of O2 sensors. You might want to read here what OBD2 code P0172 actually is:

http://www.iequus.com/support/obd2_definitions.php

Mike

clampjockey
08-13-2008, 03:40 PM
my mistake....its bank 1. the one on the 96 has 2 wires (upper o2 sensor) my 94 has 1 wire and my 92 parts car has 1 wire.
so if the 4cyl only has 1 bank, it could still be either one the top o2 sensor or the bottom.

Brian R.
08-14-2008, 12:53 AM
If the sensor after the cat converter were bad, you would get a cat converter code, not an HO2 sensor code. It almost has to be the top sensor near the head - the one that controls the fuel/air mixture in closed loop.

clampjockey
08-14-2008, 07:58 AM
o.k thanks guys. should i maybe change the cat or eliminate it? could it be gumming everything up? the engine was blown in the 96 when i got it (literally holes in front and back of the engine block), so i took a block from a 92 that had a bad head gasket and mated it with the head from the 96. the head from the 96 was FULL of carbon build-up, which brought me to thinking the cat might be plugged. does that make any sense? could a plugged cat be giving me a faulty 02 reading?
also, yesterday i was calling around pricing o2 sensors, everywhere i called said they fit from 92-96......but the upper 02 sensor on the 96 has 2 wires and a 2 prong plug......my 94 and 92 parts car both only have 1 wire and a 1 prong plug.

Brian R.
08-14-2008, 11:04 AM
A bad cat converter will give you a bad cat converter error code (Sensor 2). You most likely have a bad sensor #1 - next to the head - since you have a bad mixture.

Call a Toyota parts department and give them your VIN so that you get the correct sensor. You don't have to buy it from them unless you can't find any other source, but get the right sensor.

There is a chance it could be a bad ECT sensor or a fuel problem like a leaking injector or bad pressure regulator. Most likely is a HO2 sensor.

clampjockey
08-14-2008, 02:25 PM
Thanks Brian
Update
i reset the check engine light with my super cheap e-bay version of an obd2 reader, then unplugged the upper 02 sensor and took it for a drive. it ran a little worse than before, when the engine light came on i got code 0125 " Insufficient coolant temperature for closed loop fuel control"(my sisters corolla throws the same code). so i plugged the top 02 sensor back in and unplugged the bottom one, reset the code and went for another drive, when the light came on it was code 0172 "system too rich (bank1)" so now i'm thinking its the bottom one. would the bottom one being faulty cause it to be a little hard on fuel (about 100 mi less per tank of fuel than the 94) and idle rough? there is also a rip in the intake hose and it sucks air up near the throttle body opening.....i have a new one ordered but it isn't in yet.

Mike Gerber
08-14-2008, 04:00 PM
"there is also a rip in the intake hose and it sucks air up near the throttle body opening.....i have a new one ordered but it isn't in yet."

You have unmetered air entering the throttle body. Cover the rip up temporarily with duct tape and take the car for a ride. Does it idle any smoother with that rip closed off? If so, you may want to clear the code again and take it for a ride and see if the code returns. It probably will, but you never know.

Mike

clampjockey
08-14-2008, 07:39 PM
thanks mike, i'll try that if my new one isn't in by tomorrow. now that my gf is home i finally got a chance to look at them side by side. the bottom o2 sensors are the same on the 94 and 96, the top ones are different. the 92 doesn't have one up top, but the one in the cat is the same as the top one on the 94. i unplugged the bottom one on the 94 and took it for a drive to see if it acted like the 96 but it didn't seem to affect it at all. i think i'll wait until i get the new intake hose before i buy or swap the bottom sensor.

Brian R.
08-15-2008, 12:55 AM
Your MAP sensor would mostly compensate for the rip in the intake hose. I doubt replacing the hose will do much more than keep your air filtered, but there will be a small difference. Your IAT sensor will have a more accurate reading, but that's about all.

clampjockey
08-29-2008, 06:42 AM
i put the new hose on now its acting worse....just ordered the new 02 sensor, i'll see if that makes any diff. thanks for the help thus far.....i'll keep you posted.

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