Rear O2 sensor bypass/CEL fix.

This is on my list now

 

do you put this in line WITH the blue and white connected at both ends or does this bypss sensor and send signal without ever going into sensor? anyne ever had probs with plastic outside clip having one less notch?

 

all the recycle centers sensors I found have 2 notches where this one has one

 

Yes and yes. Don't know about the last. Finish the harness circuit between blue and white with the mod. Make sure you use the wires going back into the harness,,not the ones you just clipped off the sensor,,savvy??. You will make a dummy loop circuit,,lol. It tricks the comp into thinking the sensor is reading ok. Don't touch the black wires with anything sharp or dull. Report back if it helped or whatever the outcome. Good luck.

 

ok had to buy sensor..the resistor mods had no effect because mine wasn't showing ready,,It has to show READY and be bad for THAT mod to work.So Ineed to drive it...lost the one bad code...So Imma drive it tomorrow for about 100 miles and see what happens

 

the mod I tried SEVERAL version until I found end...you have a guy in an O2 thread that says he CUT the wire to the sensor and put the cap and resisitor in a loop went from cut blue to cut white towards clip...Doesn't work the only one that LOOKS like it might haven't tried but MY SENSOR WASNT BAD it wasn't showing ready..and MOD only work when sensor isbroke and showing engine light

 

Posting this info in the hope of being useful to someone. I have a 2000 2.7l 4runner with 310,000 miles. It started throwing P0420 codes during the summer a few years back. Tried this mod and (correctly!) wired in the resistor and capacitor. Went about 300 miles before I got a CEL on with a P0136 code. It was the first time ever for the P0136 code. Reset it and crossed my fingers. It has been since May and 5,000 miles and the CEL has remained off with no codes being thrown. I did notice something interesting, though. The Cat readiness monitor still shows "not ready". However, I was able to pass emissions with that one not ready. It's my daily driver and I have not noticed any effect on gas mileage.

 

How time flys. Howdy to all! 4 yrs on this mod here. Total time since its inception back in 2002 is 12 yrs. I take no credit,,just saying. I would give it a 25/75 on failure and success for all who gave it a whirl. Still have it in,,light is still off. Mpg and "hill pullage" is dependent on if it is plugged in ,,or not. Slightly better with it in, remember at the beginning I mentioned I had no Cat in place, I am still straight thru. Lucky with that I think. Pure luck. Thanks for the revival Oldrusty,,and welcome in the door.

 

Is this for the 'test pipe' mod?

 

Yes... Or if you are getting a P0420 catalytic converter below efficiency threshold check engine light even though you have a catalytic converter.

 

Just out of curiosity, does the test pipe mod really free up engine power?

 

not that much if any if you have a relatively clean cat. if you have a partially clogged cat to begin with then it would probably help.

 

Not specifically. More of a "turn the damn light out". Never even knew a test pipe mod existed at the time. It did free up a bit of hill power and a touch of mileage with the gross weight of the truck unchanged. Shouldn't have, but it did. I believe I added the OEM mini header after this mod. No real change. A better engine note from about 3-4k rpm with it all cleaned up.

 

6 month bump.

I have the rear o2 CEL this should fix. But I also wanted to know if this, or any other method of cobbled electronics, could totally eliminate the rear o2 altogether. I’m contemplating just going catless from header back and putting a really quiet muffler in under the bed with it dumping in same stock location. It’d save having to weld in the special o2 bung used on these 1st gens. Which would eliminate another potential rust/failure point 5 years down the road.

 

Well, I dunno. At least in my case this morning, got the P420 code after I installed my replacement (rear) converter. Code was cleared before the install and I have the URD simulator installed. Had it installed for years, just got around to putting the cat back on. I had the test pipe in prior to this that is why I had the URD simulator.
Can't explain the P420 code at this point because I have both a new cat and the URD installed.

 

Crazy. There might be conflict still. Maybe yank the URD plug while it is running. Shut down and pull the batt cables off for a plugs-out reset. Let it set overnight disconnected.(the capacitors drain off a bit.) Reassemble at the crack of dawn. Give it a twist. This fixed a buddys 2006 V6. Yanking the rear o2 sensor plug,,while it was running, then a full disco overnight. It slapped the computer and cleared the code. The magic key??,, yet to be proven.

 

A bit easier said than done at least with my URD. Had it for years, it is hard wired in. Might try the battery disconnect thing though.
Has me wondering if I needed the California cat. My engine code is strictly to California emissions, not 49 state. Bought truck new in Ohio where it has been ever since, not sure why it is California emissions. Wondering now if the engine control computer is looking for a different signal from a more restrictive California cat.

 

A little late to the party, but just wanted to chime in.

The CEL on our 2012 Camry was persistent after our daughter hollowed out the catalytic converter. We tried the spark plug anti-foulers, and that did not work at all. We found this schematic and tried it. First with the 1 resistor, and 1 uf cap. That did not work. Then we saw the schematic with 2 resistors. Tried that, and it did not work. Then, we saw using a 4.7 uf cap. Tired that, and it did not work.

After all that, we ran across this thread and saw the PIC you posted. we decided, you know what-- let's try the incorrect version. Believe it or not, that is what FINALLY WORKED!!! No nintendo, but it is what it is.

Just wanted to post here to let everyone know that things are going to vary.

 

light is back on now...............

 

UPDATE 11-17-23

After looking at several different diagrams of different ways to bypass the o2 sensor, and trying several different variations, NOTHING worked on our 2012 Camry.

Sat down and reviewed several different diagrams, and something didn't sit right. It was like they were incomplete. Went ahead and designed my own version of this bypass.

Used 1 - 2.2 UF 50v capacitor, and 3 - 220k Ohm 1/2 watt 5% resistors. NOW- the light is out completely. If anyone else is still having issues, try out this. It worked great here.