02 sensor simulator

I have a 2005 Tundra and my cat has gone out, hence I am using this as an excuse to convince the wife to let me put some headers on it and remove the cat the downstream sensor has been throwing the p0420 code for about a month now. I was posting here to see if I could get my hands on a 02 sensor simulator that generates a constant voltage sign wave would it fool the computer or do I need something that fluctuates slightly to follow the upstream sensor to be able to trick the computer into thinking the original equipment is being run. as far as I can tell, 95% of the o2 simulators that were on the market no longer exist because of the EPA cracking down on this sort of device although I have found a few and am asking yall with yer experience with a constant voltage sign wave generator and its functionality in faking the downstream o2 signal.

 

I've got a used URD o2 simulator on my 03 and it works great. Last I knew URD hadn't started making them again yet. They stopped for a few years because the whole diesel gate thing made "emissions defeating devices" illegal.
I'd check www.urdusa.com
But I also tried that same O2 sim on my 06 and it didn't work at all. So instead I put an o2 spacer on each rear sensor and haven't had an issue sense.
I live in an emissions inspection county in Texas, so every year they hook up to my OBD2 and I've passed everytime so far. I do have cats though, they are just cheapos, and the ECU's on my Tundras didn't like them after a month or two on the 03 and about two or three years later for the 06.

Your mileage my vary

Oh also, if you don't have emissions inspections, but just want the cel to go away, you can get your 05 tuned via VF Tuner, and actually have the rear O2 sensors turned off. But I don't think you can pass inspection with them off. I think those monitors would be in a constant state of "not ready"

 

What's the proof on this? Cats actually failing on these trucks is very uncommon, especially if you're only at 110k miles.

 

I doubt the ECU is looking for a sinewave. More of a DC signal between a certain voltage threshold. I would just build one myself. Maybe passively if you have a large electrolytic capacitor to use with a resistor.

 

@Jimboboss302 this happens so commonly we had to put an entry in the community megathread:

• Cat inefficiency codes P0420 and P0430: Strong chance it's not your cats. Read why HERE.

I understand the desire to run long tube, I'd like that too, but based on the couple of members on here I know running long tube headers, you're essentially locking yourself into a lifetime of constantly fighting codes, and/or having your check engine light always-on so you end up missing bigger problems.

 

Some jurisdictions also allow one system to be 'Not Ready' as long as everything else passed. My county in TX is one. I used to have a Subaru with a P0420 that I could get to pass every year.

 

In the past month or two, I've been towing hay through the hills of Missouri, putting about 10k of HARD miles on the truck towing an EXTREMELY overloaded trailer on back country roads often holding WOT to make it up hills. this truck has really impressed me with how good It can do towing way more than it is rated for. I had a Duramax I was using but I suspect the crank is broke. I was expecting something to go with how hard Ive been pushing it but the cat was not the first thing I expected to go, I thought the diff or trans would first. whoda thunk

 

If I were you, before I dropped a single dollar on a new cat or anything else ... unless you're hellbent on LT headers ... I'd replace the upstream & downstream sensors on the driver side, given you're throwing P0420.

Something else worth noting, you mentioned previously power loss over here (though I'm not re-reading that thread to see why), all signs are pointing to "you have a bad/failing upstream AFR/O2 sensor" and should replace both sensors on the driver side.

I want to look up your truck so I can help with that, but unfortunately, I just spent 5 minutes trying to figure out whether you truck is 2WD or 4WD, because the sensor part numbers are wildly different depending which it is. Please ... do us all a favor. GO HERE, and update your "Vehicle One-Line Description to which ever of these four is correct for your truck, because - and I mean this in a friendly, ribbing way - nobody cares if it's "mint" or has 110k miles

• '03 Tundra SR5 V8/2WD SR5 AC
• '03 Tundra SR5 V8/4WD SR5 AC
  
• '03 Tundra SR5 V8/2WD Limited AC
  
• '03 Tundra SR5 V8/4WD Limited AC

The trim level (SR5/Limited) is something that Denso wants to find correct parts and the drivetrain (2WD/4WD) is critical for suspension and engine related components, the O2 sensor part numbers are different for 2WD/4WD in your year. Finally "AC" for access cab will help us with wiring diagrams, part numbers and other specs if/when you need them, since all that varies by cab type.

If you go and replace all four, which may be as cheap as $200, I think you'll find your truck runs and operates markedly different. I suspect you've had power issues gradually worsening for a while now, and new AFR/O2 sensors are the only thing standing between you and the extra power you should expect.

 

PS - if you really want to flex on the miles/condition of your truck, when you hit that profile "GO HERE" link, update the "Custom Title" to say MINT 1ST GEN 110K MILES or something, and that may be a great way to advertise your love.

(Note, my truck has 81,500 original miles and is mint too )

Don't forget to click the "SAVE" button at the bottom of the page any time you update those fields.

 

its an '03 Access Cab sr5 v8 4wd with the blown cat. the last forum post was on a '05 v8 4wd access cab that I had gotten from a friend on a deal and I have since given it to my mother.

 

Aaaaah, that makes more sense now.

Ah well, good reminder to update your profile, I guess

 

magnum wins again.
https://www.magnumtuning.com/en/detail/ez-cel-fix-oxygen-sensor-simulator/toyota/tundra

 

Cornfused….help us help you, you started this thread last night mentioning 2005, now it’s a 2003

While it doesn’t matter in a way, the suggestions about replacing driver side O2’s for any year 1st Gen is valid given our cats, while subject to going bad someday, can go 100 of thousand miles before that.

 

Is there a step-by-step guide for the particular sensor cause from what I've read it is a connect this and splice that connection but different sources have said different stuff.

 

My apologies, sat down at the computer after a day at work, that was an error on my behalf. had a 05, gifted it to my mother as her Chrysler minivan had kicked the bucket.

 

would this emulator work as it's much cheaper and appears to do the same thing.

$18 BAIMOQI Easy to Use Car O2 Sensors Signal Simulators with Multifunctional Diagnostic Capabilities for Emission Testing Diagnosis, Approx.70x44x18mm, As Pictures Shown

https://www.amazon.com/dp/B0D9JV2KTC. I have also read about spacers but would my inspector flag that as no good?

 

Had a old pathfinder (these were notorious for the small acceptable range for the rear O2 sensors) and even after the dealer update it would trigger. Search for the simulator circuit. I built mine for <$5 including the prototype board. I had to provide 12v on start, then cycle between 1.0 and 1.7v while running. Just had the 555 timer chip use the voltage divider with a capacitor to provide the changing voltage input.

Actually was able to tap the sensor input at the ECU so it lived under the dash. I did add a couple LEDs to verify it was working.

I think the data sheet for the 555 timer chip even has a workable circuit design for this.

 

I don't know about a lifetime... But yeah it'll require some troubleshooting, and if I'm honest the price of admission is outrageous for the little payoff.
They said, I run cats with my long tubes on both trucks.

 

Knowing how much shit you could fry on your several-thousands-of-dollars truck using shit made in mainland China as cheaply as possible, with little or no quality control testing, and no repercussion to you if it does fry something ... I gotta ask: Why in the hell would you even consider that?

I will NEVER buy something from these bullshit all-caps-random-letters companies you find on scAmazon. You have absolutely zero legal recourse, and the quality is absolute garbage 75% of the time.

 

2.6 stars, what could POSSIBLY go wrong?

 

It boggles my mind...

Sorry (not sorry), but I absolutely will not install no-name-brand electronics sold on there and fleaBay in my vehicles.

And at this point, after the number of knockoff parts I've gotten from their warehouses, whether auto/appliance/small engine/whatever, I won't buy anything name brand from them.

 

Seriously try the spacers, they're cheaper than new sensors. If that doesn't work combine spacers with new sensors. If that doesn't work, email gadget at URD and big em about making the O2 sims again. His stuff is proven and well known among Toyota enthusiasts.

 

With all due respect, the solution to your problem was already given to you by @shifty` : replace the upstream and downstream sensors on that bank. It's $100 for both sensors at Rock Auto. That will correct your p0420 code. If you really want to do it right, replace the sensors on the other bank too and your truck will likely run much better.

 

Check out that magnum I linked though for real, it's what I used on a Honda H22. it has nothing but 4 and 5 star reviews and the only complaints are about shipping speed.
If you are determined to cheat, that is the way to do it.

 

I built that (capacitor/resistor) for my Civic when the exhaust rusted out and I put a test pipe in until I could afford an 800 dollar cat....
https://www.youtube.com/watch?v=qHD7T7EhuzI&ab_channel=MITEEman

 

glad to hear i wasnt the only one, my prelude rusted to swiss cheese. LOL. that dang H22 still ran strong as ever and the rest of the car rotted around it

 

Yeah, it would’ve been nice to see the upstream sensor along the same timeline as well. Ideally, with a good upstream, the average dc value with an ac blocking filter should be around 0.5V in closed loop mode. That video at least shows the ECU isn’t too picky and may only be looking for the number of lean/rich transitions or some comparative value between the upstream and downstream.

 

Do you got a link for the spacers that work on your 06? I have an 06 with both p0420 and p0430 on original cats. Mpg is still decent and they don’t appear to be clogged. I just want the CEL gone. I don’t have any testing or anything to worry about.

I saw you posted this as well, but I’m a bit wary of getting it tuned. I’d rather just fool them.

A bit more information on truck. 193k miles. Recently replaced plugs, maf, all 4 02 sensors, cleaned throttle body, and air filter, After clearing cat inefficiency codes they still come back within 10-15 miles. Like I mentioned above, no testing so I just want the CEL gone in case the constant light could hide a more important code.

 

Just search for o2 spacers. Most the kits come with a variety so you can figure out what works best for your truck.