My check engine light came on yesterday, so I had a code reader pull the error.

P133
O2 Sensor
CKT Slow Response
Bank1 - Sensor 1

I'm not sure where to find the o2 sensors and which one is sensor1. My Chilton's book sux..

Thanks

 

You don't mention what truck or engine but since it's a "P" code then it's at least a '96 vehicle.

There are probably two O2 sensors on your truck, and "bank 1 sensor 1" is the "first" one as you trace a line from the engine to the tail pipe. Get under the truck and follow the exhaust system from the engine to the rear. You'll see the pipes coming down from the engine and then together at the "collector". From the collector there's a short run to the "catalytic convertor", then from the cat to the muffler and the muffler to the tail pipe.

The B1S1 O2 sensor is in the section of pipe between the collector at the cat.

This may be a "one time" code for you, but a P133 will usually come back. If you didn't clear the code after you read it, you may want to do that and see if it comes back.

If it does (and again, it probably will) then you'll want to replace the front O2 sensor - I don't know of much else that can throw a P133. The best prices on O2 sensors come from URDUSA:
http://www.urdusa.com/Merchant2/merc...tegory_Code=O2


Good luck!

 

Thanks Mark,

U have a 1996 4runner Limited as well. What's strange is I got the same error about 4 months ago and changed my plugs, plug wires, and cleaned the throttle body.(Shop said those needed replacing also) The code was cleared and hasn't come back on since yesterday. It has since been cleared and hasn't come back on yet.

Just for kicks...where would the second o2 sensor be located?

Thanks again.

 

Keep following that pipping out the back of the cat and it'll be right there in the top of the pipe before the muffler.

From what I know, the P133 code will pop up when the ECU (the engine computer) sees the same result from the O2 sensor after "n" samples. In normal operation (i.e., when you don't have your foot to the floor) the O2 sensor will be sending constantly changing data to the ECU. The ECU looks at ("samples") this data a few times/second, and it's expecting it to change pretty radically. So when it doesn't, then it figures something's up.

Everything else you did was a good idea anyway, but it sounds like the O2 sensor is next on your list. fwiw, the 2nd O2 sensor _rarely_ needs changing, and there's no reason to change it if the ECU isn't complaining. i.e., don't change the rear one just 'cause you're changing the font one. The rear one is there to help the ECU decide that the cat is doing it's job by making the air cleaner, the front one is there to help the ECU adjust the fuel mixture in the engine.

It's a pretty easy change to do this yourself btw.. Though depending on where you are in the country, you may have some rust issues to work through.

 

Hey guys,

I got my O2 sensor yesterday and found the location. There appears to be two bolts that hold it on. The bolts don't look like they are squared off though. For those who have replaced theirs on a 1996..What tool did you use?

Thanks

 

A deep socket... They're normal hex nuts, but depending on where you are in the country, they could be WELL rusted. My truck spent it's first 4 years in Chicago, and when it came time to replace mine it was quite a trip.

Use a lot of PB Blaster; soak it a couple of times a day for a week and you should be in a better spot.

You're replacing the one in _front_ of the cat, right? There's rarely a need to ever replace the 2nd one (after the cat).

 

Thanks midiwall,

Yea just the front...It throws an error code every few months then goes away..However, my mpg has seemed to have gotten worse, so I'm going to replace it now..

 

I just used the closed end on a cresent wrench or a flex head ratchet with a deep socket.

Definately soak the crap out of the stud if it has been anywhere near a rust belt.

Ditto on the front O2 sensor only....replace the other only when you get a code for it.

 

Thanks...Do y'all remember the size of the deep socket?

 

10mm or 12mm... I think it's a 10mm.

You might want to look at buying a set of those ratcheting box end wrenches instead. They're about $35, but they'll be VERY helpful in the long run, probably moreso than deep sockets.

 

I would say 80% of the 4runner's bolts will be a 10mm or 12mm but I don't remember which it was offhand, just get under and give them a shot. I agree the ratcheting box ends are very helpful in a good portion of the time as well.

 

I used a 10 mm wrench when I replaced mine a couple of weeks ago. I also got the O2 sensor from URD. It improved my gas mileage as well.

George

 

always remember with japanese autos...the 2 most important sizes are 10mm and 12mm. 80% of the time you will need those. except when u change your oil, then you need 14mm.

Also, do a search for MAF and throttle body cleaning. Do the following before replacing that O2 sensor:

clean MAF and throttle body
check wires and spark plugs (replace if needed)
clean/change air filter
clean O2 sensors with electrical contact cleaner.

If you still throw a code, then replace that O2 sensor as a last resort. doing all the above will still be cheaper than buying a freaking new O2 sensor, plus, it will help your car anyway

 

Which is also a 9/16" = 14mm

 

Looks like the bolts are looking pretty bad. Somewhat stripped and rusted. Gotta whip out the vice grips and hope for the best!!

 

Hey Guys,

I've put off installing the o2 sensor for the last month....The two bolts are rusted and stripped pretty bad. I applied pentrating spray on it for a whole week and still no luck. I've even tried vice grips, but they chew up the bolts...The "check engine" light came back on today so I need to do something..

Anyone have an ideas on special tools to remove stripped bolts? I know Sears has a set of sockets that will do this, but I don't think they come in deep sockets..

Thanks

 

did you ever figure out how to get the bolts off??......i'm about to do mine and I know for certain my runner has been in the snow belt in ohio, so its got some rust, did you try the box end ratchet wrenches?

 

Mason,

I actually had to use a dremel tool to cut into the bolts. I cut in just enough to knock the bolts with a hammer and flat head screwdriver.

 

HI- I am new to this site- I was wondering if you could help me. I need an air flow control (?) for a non-USA spec pickup truck- VID#VOT2259812U2U125D.
The truck is out of the country and I need to send this part ASAP. I have been told it is the control that opens the flap door in the air intake sleeve. Any ideas- USA parts houses don't seem to carry this part. Any suggestions will be greatly appreciated. Thanks.
chas3840

 

chas,

welcome to yotatech. your best friend here is the "search" feature. in fact, if you search "02 sensor writeup", you will probably find mine which shows you how to do it in excruciating detail with pics.

so search!!!

bob