oldanteek

What is this fuel/air sensor? That's not the mass air flow sensor is it? If this was bad would is kick a P0420 code? I will do my homework and report back what I find. As far as replacing the cat, I get varied opinions, but sure hate to put a new one on and still get the code. If I did, would I put and OE or find an after market to fit? Also, if I do just replace the rear O2, which one should I use? OE or another? Any suggestions is helpful. Thank you!

GEORGE_JET

a/f sensor is the next generation of O2 sensor, that is what your engine uses to adj the mixture, (along with MAF, throttle position, temp, etc. You have two of them on your car, one on each bank. The fact that your fuel trims are that close, indicate they are working. You have a third O2 sensor, which is a older style, located after the main cat, this is the one that monitors the cat and sets the code. Do you know if your car passes emissions (besides the fact that the light is on)? Right now I am looking at a device that may be appropriate for this type of situation. I will let you know later after I get more info.

oldanteek

We do not have emissions testing where I live in WI, so I wouldn't know if I would pass or not. This is something I can look into having done to see where the numbers come out. So if I were to replace the O2 in the rear, would I use the new A/F sensor or the older O2 sensor like currently on the vehicle?

GEORGE_JET

EBAY autction #110383422531
Universal Oxygen O2 Sensor Simulator V2 w/ Heater Sim

I have been looking at this, it appears that would work for what you want. To Install this, unplug the sensor (located underneath the car, behind the rear cat, not the two front sensors). On the sensor side of the harness, cut all the wires app half way between the sensor and connector. You want to leave enough wire in case you later decide to hook it back up.

Now as far as passing emmision inspection, good question. This circuit should fool the ECM into thinking that all is working properly. So your check engine light should remain off. So is the universal cat working well enough to pass the sniff test?? Who knows? My quess would be probably, but that is only a quess. By cutting the wires on the sensor, you leave your options open to going back to original.

llcoolpass

lolololololololol

oldanteek

This O2 on Ebay may work, but I just replace the rear or do I need to replace more then1?

GEORGE_JET

The simulator is used instead of the post cat sensor. It supplies a signal to the ecm, so that you should no longer have a check engine light.

oldanteek

I emailed the guy selling and he advised the front O2 is the primary sensor and the computer solely relies on the AFR value from it tooperate the car correctly and should be OE, not a SIM, but the rear 2 would need to be the SIM's to get it to work.

you need simulator(s) to replace the rear o2 sensor. these secondary o2 sensors are purely for emission purpose and they can be replaced.

as i said, v6 / v8 etc engines are divided into multiple banks and they have two rear o2 sensors. that's why you need two sims.

GEORGE_JET

Yes, the simulator is for the post cat sensor only, Do not use it to replace the pre cat sensors. I re-read my post, and now realize that I wrote it poorly. I should have be more clear on exactly which sensor this is to replace.

oldanteek

The guy who is selling it, says I may need two not just one. Could you "ask a question" on the auction for clarification. Thanks!

GEORGE_JET

Check underneath your car, after the cat (app the middle of the car, there should be 1 O2 this should be bank 1 sensor 2). With this configuration, the auction number is the correct part. Pardon some of my earlier wording, I started off on conventional engine layouts, before transverse layouts started getting popular. I think of a v6,v8 engine layout as right / left bank with the rear being the rear of the car. When I said rear, I mean towards the back of the car.

oldanteek

OK George, I ordered 1 O2 and received it yesterday. I will replace the 1 post cat O2 with this SIM and I will let you know what happens. Heres to crossing fingers.

GEORGE_JET

Thanks, I am interested in hearing how it comes out. I have read about people bypassing the cats, and then using them without a problem. Of course with gutted cats they will never pass emissions.

rlx101

this is interesting. i also have PO420 (on 2002 es300) but it keeps going away after the car is not driven for some time, i was on vacation for 2 weeks and the code disappeared. now i've been driving it for 4 days and the code still has not come back yet... weird. im curious to see what the results will be with this simulator.

EDIT: apparently people have been using these simulators for a while with after market parts.. here is DIY with Electrical diagram how to make your own simulator: link

so as long as cat converter can pass emissions this should be a relatively cheap solution? nice.

hank2004

hi! George and all,

Can someone please direct me to some info on the net re. ES330 P0420 Bank 1 A/F sensor non responsive, Catalyst system below efficiency threshold.

2004 ES330, just passed Cal smog test 9k miles ago at 40,000. Don't think I can use the same method of by-passing the catalytic signal cuz I am in calif. How can a 49K mileage car have this emission problem. Used to have a supra that passed smog test at 184K miles. I can't afford going to the dealer until getting a permanent job.

Thanks