oxygen sensor bypass

URD makes an oxygen sensor simulator. It's here http://urdusa.com/p1260518914/URD-Rear-O2-Simulator,-2RZ-FE-2.4L-,-3RZ-FE-2.7L/product_info.html

I have been clearing the p0420 code that tells me one of my cats is dying or one of my sensors are dying. I'd rather just swap this simulator in and never deal with cats again as i live in a state that never tests. and if this doesn't fix the problem then i'll just have to swap sensors and then the good one will be in the front and the bad one will be in the back of the cats and the simulator will tell the system the bad one is still ok. my question is am i reading the description right in that your front sensor has a reading and if your cats are bad then the back sensor reads fault and this simulator just tells the computer that the back simulated sensor is reading a perfect exhaust gas?

 

Yes. Same problem on mine. That's what I have installed and no code.

 

Great. If the code pops up again i'm throwing on a header and eliminating my cats and putting in the simulator.

 

Careful with that. I would do more research. Because that's what I was gonna do and if I remember correctly I was told online and by a mechanic that the front cat is needed. Can't remember why tho. Most guys just do a rear cat delete. And in my opinion, a header is not worth the price. Unless you are getting a supercharger. Even then I doubt the gains will be worth it cuz the supercharger is just a bolt on and kinda lacking in gains itself. I haven't done mine yet.. But I plan to get all that done eventually.

 

On early OBD2 vehicles (all 1st gen Tacomas) the rear o2 ONLY checks the cat. When you look at it on a scope it will be a steady voltage. I am running a URD o2 sim on my 96 Tacoma. It cleared my P0420, and I have had it inspected since. It plugs inline with the sensor. takes 3 minutes to install.The front o2 measures the air/fuel mix and the computer adjusts based on that reading. If that sensor goes bad, or is MIA, you will get really bad mileage. you must have that sensor.

 

Technically the cats are not needed to run but the front O2 is.

 

I am going to continue to run both of my o2 sensors. I was saying if the one in front is bad then i'll switch it with the back one just to get a functioning one in the front because the back one will be useless.

 

Not sure on the 2.7 but the front sensor on my 3.4 is an air/fuel sensor and is not the same as the rear O2 sensor...the front one also costs about twice as much, so I don't think they are interchangeable. I'm guessing the same is true with your 2.7, unfortunately.

I just replaced the O2 sensor on my truck. It was about $52 on Amazon for a Denso. The parts places all seem to carry Bosch, which I understand doesn't work well in Toyotas. I just unbolted my exhaust behind the cat and dropped the pipe down to get at the O2 sensor nuts that are kind of hidden behind a heat shield. Probably took all of 30 minutes, but my exhaust is new from the cat back. You may not be so lucky.

 

i'm still almost a 100 percent it's my cats dying that is popping the code. I'll know for sure after i hook up the simulator. So i doubt i'll have to mess with my o2 sensors

 

Sorry to thread jack a bit but.. And I'm sure there's threads out there regarding this but since I'm here..

Is it possible to delete the front cat (and rear) and just weld in an O2 bung to the pipe for the front sensor? And what would you do with te rear sensor with the simulator, just leave it unbolted and tie it up under the chassis out of the way?

I have an exhaust shop I will be going to eventually and was planning on just doing the rear cat delete but wonder if it'd be worth it to delete the front as well if possible as to prevent it going bad in the future.. High flow bolt on front cats are crazy expensive.. I'm sure the exhaust shop could weld in a cheaper one too and angle it down from the manifold, but it would be easier and cheaper to run straight pipes with a muffler, turned down before the rear axle. $400-500 I was quoted. Plus whatever muffler I supply for them to install..

 

I don't know about your muffler shop, but the ones around here won't delete cats. I was told by the one I use that there's a big fine involved if they get caught deleting emission control devices. He just would not do it, so I went with a cat back that he built. I don't think he would have turned down the extra money he could have gotten for the full exhaust, so I believe what he told me was probably true. In fact, I think he had a sign posted in the office about it as I recall.

 

Why are you wanting to delete the cats?? There is no real gain in not having a cat...

 

Hit the cat with your fist and if you hear a rattle more than likely it's bad.

 

The last time I got my newsletter at the shop it was something like a $100,000 fine for a shop getting caught removing or altering federal emissions control devices.


The earlier poster was correct on not being able to swap out the two sensors. The rear one is an Oxygen sensor, the front one is an A/F sensor. They will both bolt in and plug in the same, but the O2 sensor will not function properly in the front position.

 

Thanks for the update on that Bama. I think when he told me that the fine was about $20,000, so it has been some time ago, but even that amount would be enough to deter me. I'm not a fan of federal emissions control devices (or federal control in general), but I certainly wouldn't want to put anyone in risk of a fine like that either.

I was also the earlier poster on the sensors. I figured the 2.7 would be the same, and you have confirmed that.

 

Well I was just wondering.. I cant remember if I asked the shop if they would do it or not. Unless there's some new law.. But I too live in an area that doesnt require emissions. I suppose it's better if you leave at least one on there in case I move to an area that does require it. I was planning on doing just a cat back anyways, just was curious if that was possible cuz if so it would be a little cheaper is all.. $250 just for the front direct bolt ons. Plus whatever the shop charges me so could be close to $800.. Wanted to keep it around 400-450 for my budget.

 

Regardless of if you need emissions testing or not wherever you live, it is still federally mandated in EVERY state, that a shop cannot legally tamper with or alter any factory emissions control devices. Now that doesn't mean you can't do something on your own truck. But a shop can't.