guys,

96 4Runner with 5VZFE and 3 pedals

I've got a engine code stating bank 1 sensor 1 oxygen sensor is not functioning correctly. I've reviewed the FSM just to confirm location. To my surprise I could not locate it in the pile of pages online. Can you confirm the location of said sensor? Is it the one before the cat?

Lastly, any advise on removing the sensor after 14 years.........the nuts are so rusted. Oh the horror.

much appreciated....

 

We need the engine size and also the year of the vehicle .;

 

ya got me.....edit complete

 

Sensor 1 is the front sensor (before cat). Bank 1 is the only bank on the 5VZE-FE. Just get new nuts. The good news is the studs are a lot tougher than the nuts. Mine were toast and just crumbled under my pliers. Also used a socket a size or two smaller than the original. They eventually came off in little pieces. Then I cleaned off the threads and the gasket surface, and popped on the new sensor with a lot of anti-seize on the threads.

 

Where did you get the codes out at.... Did it say Heated O2 sensor circut or low voltage.... With the age of the vehicle its prob bad.

 

Here's a good write-up if you replace it:
http://www.4x4wire.com/toyota/4Runner/tech/O2_Sensor/

 

chip or chisel the old nuts off

bash the sensor loose to free it

chisel the remaining gasket off the bung to make it smooth

wire brush the studs

try to to let too much crap fall in the hole while doing this

 

this write up says that sensor number 2 should not affect gas milage but when mine went out i saw a increase in gas consumption. just curious if my sensor 1 is also bad. the code i had referred to sensor 2 and after replacing it i noticed the truck performing better.

 

Your front sensor could be going bad as well. It may not be bad enough to trigger the Check engine light though. Both of my o2 sensors went out within a month or two of each other.

 

Here's another pictorial.
https://www.yotatech.com/forums/f2/c...rusted-197311/
My front sensor came off easily just like the writeup. Note the studs that still look great after 130K miles. The nuts themselves have 45K miles on them (yes my front A/F sensor failed after 45K miles).

My rear sensor which is throwing codes now, appears to be on a bung that was installed by my exhaust guy less than 30K miles ago. The studs themselves are rusted to hell. Definitely not the stock bung/studs. That one will be a biatch.


By the way, Amazon is the way to go for A/F and O2 sensors. I looked high and low and could not find a price lower than what Amazon charges for genuine boxed Denso sensors with gaskets.

 

where did you end up finding the new nuts? or should i just goto the dealer for those?

 

Here's a bit of interesting material.....due to the bad O2 sensor I feel the engine has been running rich. First- the fuel mileage has really diminished the last 4-6 weeks. Second- because I have an early TRD supercharger I've got a bit of knock at low speed with a higher gear. (just part of TRD not fully upgrading the fuel system) but I have not had the knock in quite a while. Indeed if the engine is running a bit rich that might take care of the fuel starve issue. Hmmmmmm.

Hope those nuts come off as previous posts have experienced.

 

You did not give the exact code, but some of the front O2 fail codes will lock the ECU into open loop, where the ECU completely disregards the sensor input as it always does when you first start the car. This will definitely erode the fuel mileage. IDK about the S/C, as I have never had one.

 

if your front sensor has more than about 75k on it, replace it, check engine light or not. you will see a 1-3 mpg increase right away most likely. I went from 16 mpg average in my 4runner to 20mpg with just a new front o2 sensor.

I damaged the castle nuts when I changed mine on both my 93 4runner and 00 taco; one of the studs came loose and I boogered the threads on it as well but schuck's has new studs for less than $5 a set, might be worth it.