Hey. New to the Toyota truck community. I just bought a sweet '95 v6 4runner and need to replace the o2 sensor, problem is the previous owner replaced the flange style mounting with the screw in type. Does anyone know what screw in sensor I should put in? I have a suspicion that one currently installed is not the right one for the job as it seems to be fairly new and is performing sluggishly. Thanks! (non CA model with just one upstream sensor right before the cat).

 

Welcome to the forum, and congrats on your new (to you) 2nd gen!

The Denso sensors definitely work the best, but I don't know how you'd cross reference the proper flange sensor to an equivalent screw-in type. Did he have a screw port welded on to the exhaust pipe? And if so, why??? You might be better off visiting an exhaust shop and having them weld the right mount in place so you can use an OEM Denso sensor.

(Rock Auto does show an NTK screw in sensor for your vehicle, but I don't have any confidence it would work as well as the Denso, if at all.)

Hopefully you won't find too many more "engineering changes" on your new vehicle.

 

Thanks for the reply RJR. The previous owner welded a sleeve over the exhaust to remove the flange and include a screw port, my guess is that he broke the studs trying to remove the OEM sensor and this was his 'solution'. I was hoping that maybe Denso made an equivalent screw in type sensor. As you mention, I might have to return it to the stock configuration if I cant figure out a good solution. The rest of the truck seems to be in good condition and stock, other than a small lift and big tires.

 

After I rebuilt my engine, I tried an NTK and screwed around with everything else trying to figure out why it would run like crap as soon as it went into closed loop. No codes would show up which made this particularly trying. Out of desperation, I finally put the OEM Denso unit back in and like magic it ran perfectly and passed smog to boot some # of months later. So the old Denso that the vehicle came with is still working. The same thing for the spark plug wires can be said too use Denso or OEM Toyota. The OEM O2 set up has a heat shield that shares the same studs that the flanged sensor uses to fix it to the exhaust. The Denso design for the O2 sensor has some more sophisticated internal design structure which make it more robust and more able to ward off contamination to maintain its function. I just replaced the Cat-Back with a home made FlowFX and 2-1/2" exhaust over the holiday break and am almost 10K miles after the rebuild on the engine. The throttle response from 3 to 5K is very nice!

 

After I rebuilt my engine, I tried an NTK and screwed around with everything else trying to figure out why it would run like crap as soon as it went into closed loop. No codes would show up which made this particularly trying. Out of desperation, I finally put the OEM Denso unit back in and like magic it ran perfectly and passed smog to boot some # of months later. So the old Denso that the vehicle came with is still working. The same thing for the spark plug wires can be said too use Denso or OEM Toyota. The OEM O2 set up has a heat shield that shares the same studs that the flanged sensor uses to fix it to the exhaust. The Denso design for the O2 sensor has some more sophisticated internal design structure which make it more robust and more able to ward off contamination to maintain its function. I just replaced the Cat-Back with a home made FlowFX and 2-1/2" exhaust over the holiday break and am almost 10K miles after the rebuild on the engine. The throttle response from 3 to 5K is very nice!

 

I finally replaced the screw in O2 sensor with an OEM denso unit. The truck continues to run the same (actually very well, but burning a bit much gas I suspect) and the check engine light is still on. Its throwing codes 5 and 27, so O2 sensor open or short and sub-assembly O2. Problem is that I don't have a California truck... It is a Canada truck so I doubled checked to see if there should be a rear sensor, but there are no wires going into the ECU for it (or metal pin connectors in the plug), so I am thinking that it doesn't have one / need one.

Why is it throwing a code for a sensor it doesn't have? Could it be an used ECU that came from a Cali truck, is there a way to check?

Thanks!

 

Check the ecu. Some one may have swapped in a cali o2 computer. They are interchangeable but you will get the code for the second 02 sensor missing.

 

How certain do you feel about your interpretation of the MIL flashes. I'm personally a bit skeptical because they don't use single digit codes in this era of ECU.

From way over here I'd interpret this as possible code 52 and 25. 52 is the knock sensor, and 25 is a lean signal.. Now bare with me, I know you think it's running rich but that is in fact the TCCS ECU correctly responding to a lean signal "add more fuel!"

PS for what it's worth when I ordered my O² sensor from denso direct it arrived as a threaded sensor with a bolt on flange.

 

I think you might be right, this is the knock sensor wiring...