2003-4x4runner
New member
I have a V6
Trouble replacing upstream O2 sensor
- Thread starter adrianp
- Start date
How to replace O2 Upstream Sensor for 4Runner 2012 4.0L V6
Hi,
I would like to help if someone needs to replace Oxygen Sensor for 4Runner 2012 4.0L V6 on the Bank 2 Sensor 1 or so called the Driver Side A/F Sensor.
I did it by myself on the weekend, and here is the steps that how I did it with a very simple tools to do the job.
What happened is my Check Engine and its Anti-Roll lights were on recently after 95K miles on its odometer, and only after its part warranty expired at 80K miles. How irony is it?
Used the OBD2 scanner to check for its codes. As shown P10051 and P22240 where the former - Oxygen Sensor Heater Control Circuit Low and the latter - Oxygen Sensor Positive Current Control Circuit Open or Shorted, located on Bank 2 Sensor 1 - the driver side in front of catalytic converter.
Removed the sensor plug, with a voltmeter to check for the resistance between pin 1&2, and I found that it was none so meaning that the heater circuit already burned out or open.
Placed order for the part - Denso 234-9101 from Rockauto.com and now is ready to install it.
See the pictures and its itinerary steps had taken to replace the sensor.
Some extra things needed to mention at here:
1. Use the 22mm Oxygen Sensor socket which is available at any auto parts store.
2. Do not use one piece 18 or 30" long extension bars due to its rigid and very difficult to insert behind the engine against its body frame. I used several shorten ones and taped it to hold down together for its flexibility. Insert the O2 sensor socket into the sensor first and then extension bar from bottom to the top. Do not go from top to bottom. Align socket and extension bar then hold on its length to pull down to close it.
3. Spray WD40 into the sensor threads to get loose some rusty stuffs.
4. Start to turn CCW from the top as shown in pictures to remove the sensor.
Hope that it will help.
Cheers.
Hi,
I would like to help if someone needs to replace Oxygen Sensor for 4Runner 2012 4.0L V6 on the Bank 2 Sensor 1 or so called the Driver Side A/F Sensor.
I did it by myself on the weekend, and here is the steps that how I did it with a very simple tools to do the job.
What happened is my Check Engine and its Anti-Roll lights were on recently after 95K miles on its odometer, and only after its part warranty expired at 80K miles. How irony is it?
Used the OBD2 scanner to check for its codes. As shown P10051 and P22240 where the former - Oxygen Sensor Heater Control Circuit Low and the latter - Oxygen Sensor Positive Current Control Circuit Open or Shorted, located on Bank 2 Sensor 1 - the driver side in front of catalytic converter.
Removed the sensor plug, with a voltmeter to check for the resistance between pin 1&2, and I found that it was none so meaning that the heater circuit already burned out or open.
Placed order for the part - Denso 234-9101 from Rockauto.com and now is ready to install it.
See the pictures and its itinerary steps had taken to replace the sensor.
Some extra things needed to mention at here:
1. Use the 22mm Oxygen Sensor socket which is available at any auto parts store.
2. Do not use one piece 18 or 30" long extension bars due to its rigid and very difficult to insert behind the engine against its body frame. I used several shorten ones and taped it to hold down together for its flexibility. Insert the O2 sensor socket into the sensor first and then extension bar from bottom to the top. Do not go from top to bottom. Align socket and extension bar then hold on its length to pull down to close it.
3. Spray WD40 into the sensor threads to get loose some rusty stuffs.
4. Start to turn CCW from the top as shown in pictures to remove the sensor.
Hope that it will help.
Cheers.
dcavanaugh1975
New member
I'm in a similar situation with my 03 4Runner .. got the dreaded P0420 code. I do think it's my cat. But since sensor 1 is not really an O2 sensor, some A/F sensor, I can't tell exactly what's going on from the charting I've done. Bank 1 will have a sudden 0 reading, and on the next data set, Bank 2 will do the same (sensor 1 only) Possibly a short? Sensor 2 Bank 2 is following trend, while Bank 1 sensor 2 is completely erratic... After the light is on.. fairly ok prior to that. Tried with little success to pull the plug. Have all the gear mentioned heater has continuity on B1S2, and Chilton's is in the mail. But it's Sunday night... YKWIM?
Anyway, before I start changing expensive parts. Want to know what's going on. Wondering if I bought a flooded vehicle.. which could cause all of this. Noticed that the frame has 07 written on it, so there's been a frame-off in 2010. I thought finding a wiring diagram would be easier since it's a national standard.
Anyway, wanted to mention Bank 1 is always associated with cylinder #1, if ever in doubt. That's why the V6 Bank 1 is on the passenger side.
That clip on B1S1 isn't going to be so easy.
Will keep you posted. Any advice would be appreciated. Thinking the cat and both sensors, but still not sure it's not just a short. Anyone know if there's a fuse and what it's called? Thanks!
Sent from my SAMSUNG-SM-G935A using Tapatalk
Anyway, before I start changing expensive parts. Want to know what's going on. Wondering if I bought a flooded vehicle.. which could cause all of this. Noticed that the frame has 07 written on it, so there's been a frame-off in 2010. I thought finding a wiring diagram would be easier since it's a national standard.
Anyway, wanted to mention Bank 1 is always associated with cylinder #1, if ever in doubt. That's why the V6 Bank 1 is on the passenger side.
That clip on B1S1 isn't going to be so easy.
Will keep you posted. Any advice would be appreciated. Thinking the cat and both sensors, but still not sure it's not just a short. Anyone know if there's a fuse and what it's called? Thanks!
Sent from my SAMSUNG-SM-G935A using Tapatalk
Last edited:
earthrealm
Senior Member
So tried helping a pal replace his b2s1 af sensor.it was a real pita.didnt budge even after spraying wd40 for 3 days.
Gave up took it to the mechanic.
They got it out alright, but the threads were damaged, and he was unable to fit in the new sensor.
Has anyone being in this situation before?.
Am thinking using a thread chaser to smoothen out the hole and thread,
Gave up took it to the mechanic.
They got it out alright, but the threads were damaged, and he was unable to fit in the new sensor.
Has anyone being in this situation before?.
Am thinking using a thread chaser to smoothen out the hole and thread,
Last edited:
KansasCitySue
New member
O2 Sensor harness - ugh!
We got the O2 sensor (bank 2, sensor 1) out but the harness won't come unplugged and there's barely any room for 1 hand to fit in that area let alone another one plus a tool. Anyone have any suggestions????
Thank you!
We got the O2 sensor (bank 2, sensor 1) out but the harness won't come unplugged and there's barely any room for 1 hand to fit in that area let alone another one plus a tool. Anyone have any suggestions????
Thank you!
KansasCitySue
New member
I am trying to replace the same sensor! This is for an '04 Toyota 4Runner, V6, 2WD. Bank 2, sensor 1. We got it out but the wiring harness won't come unplugged! There's barely enough room for 1 hand, let alone 2 and a tool! Rumor has it there's a lock on the harness to push but we can't get to it. Any suggestions?
Thanks!
Thanks!
Last edited:
KansasCitySue
New member
My '04 sensor won't unplug! Was there a lock of some sort you had to push???
MikeinNH67
Senior Member
There's a button you need to press to slide it out. That button can be tough, pliers help and often pushing the connector on farther will help it not bind. Can you un-clip the christmas tree type clip that holds the connector to the body? That would give you more to play with.
Here's a closeup of the clip that needs to be pressed. You can see it on top.
Amazon.com
Here's a closeup of the clip that needs to be pressed. You can see it on top.
Amazon.com
MrSeth
Member
When I did mine, I sprayed the whole connector with electronic component cleaner (found at local auto stores) and let it sit and soak. There's a "squeeze lock" on it, you have to grip that with two fingers and pull on the old sensor simultaneously. Sometimes it also helps to push the two connections together and wiggle them in and out to get it to loosen up a bit from its prolonged heat exposure.
