How To: Make Your Own Rear O2 Simulator for $5
- Thread starter Robb235
- Start date
aontkos
New member
Same here. As far as I know, I followed the instructions perfectly. I ordered the same parts, did solid soldering, sealed everything well, etc.
Curious to hear what other folks have to say about this.
brillo_76
Elite Member
I thought an inefficient cat code means the cat burned itself out? I had a 2002 Camry burn its front cat out due to oil consumption.
My truck is a 2004 Tacoma with the 3.4L V-6.
One of the earlier comments mentioned making sure the capacitor is installed correctly with respect to polarity (#147). I have no idea how mine is done...I just soldered it in without even thinking about it.
Also, using my scanner, at idle my downstream O2 sensor is putting out a voltage that fluctuates between 0.41v and 0.445v. I'm not sure what that should tell me...
Can anyone shed some light on how to make sure we have polarities right?
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brillo_76
Elite Member
Capacitors are mostly marked when they are polarity sensitive. The positive lead is almost always longer then the negative lead.
Capacitors are mostly marked when they are polarity sensitive. The positive lead is almost always longer then the negative lead.
Thanks for the info and I can see what your talking about. That older comment said to connect the negative to the white wire. I'll have to check and make sure I did that. This is the capacitor I used:
E-Projects - Radial Electrolytic Capacitor, 1 uF, 50V, 105 C (Pack of 5): Amazon.com: Industrial & Scientific
It could be something like that. I started having the P0420 codes after I had a coil pack going out. It would cause misfires, most of which weren't even noticeable, that put unburned gas into the cat. I'm not sure how restrictive my cat is though.
19963.4lsr5
New member
JoeT4R
Senior Member
How were you able to determine this? Were you losing coolant at a noticeable rate?
19963.4lsr5
New member
Yes I thought it was a bad head gasket but when I pulled the heads I got sad real fast on the passenger side.
The sleeve was corroded and rusted through and had about a 1/4 cup of antifreeze pooling on the piston.
I created a post asking what people thought may have caused it. I think the rings rusted to the cylinder bore. There is a picture floating around somewhere.
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I found that I had the capacitor installed backwards, with the positive leg on the white wire. I swapped them and took the truck for a test drive. The P0136 code came back within 5 miles. The P0420 code has not returned. The voltage signal from the O2 sensor ranges between 0.29v and 0.64v. I'm not sure where to go from here.
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According to the image here the corresponding values should be:
Black = Blue
Grey = White
Just double check to make sure that both the heater wires are white! Else maybe its another configuration
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19963.4lsr5
New member
I never got mine to work. Even tried different caps for different switching frequencies.
My problem ended up being antifreeze. Fixed it and 420 code went away.
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My problem ended up being antifreeze. Fixed it and 420 code went away.
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Maybe I am just silly. When a cat burns out. I just replace the cat or fix the issue that caused the cat to burn out to begin with. As mostly, there is a cause to the platinum clogging up or burning through.
Not silly at all in my opinion. My codes started after a coil pack had failed. I think the cat is probably slightly damaged from the unburned fuel going thru it during the misfires, but I don't think it's in real bad shape. This all happened with original parts with ~250k on them. I could drive for quite a while (hundreds of miles) before the P0420 code would come up. I just ordered a new Denso O2 sensor and plan to install that and see what happens. If nothing else it'll let me monitor the degradation of the cat and better judge when to replace it.
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brillo_76
Elite Member
Could be what started it. We were having a misfire in one. Did the coil and plug swap. Stayed at the cylinder. Double checked the compression good. We had an injector fail. So I resealed all the injectors on the passenger side along replacing that injector with a new used one and bingo the issue was gone .Maybe I am just silly. When a cat burns out. I just replace the cat or fix the issue that caused the cat to burn out to begin with. As mostly, there is a cause to the platinum clogging up or burning through.
Not silly at all in my opinion. My codes started after a coil pack had failed. I think the cat is probably slightly damaged from the unburned fuel going thru it during the misfires, but I don't think it's in real bad shape. I could drive for quite a while (hundreds of miles) before the P0420 code would come up. I just ordered a new Denso O2 sensor and plan to install that and see what happens. If nothing else it'll let me monitor the degradation of the cat and better judge when to replace it.
Another thing I seen folks do is pull the 02 sensor out a little further if it's the rear one as they monitor how the cat is doing...
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19963.4lsr5
New member
Pull the pipe off the back and look for melt through. It’s two bolts and a gasket.
Toyota does a poor job of detecting missfires and flashing the check engine light. Most people ignore the flashing light and keep driving anyway.
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Toyota does a poor job of detecting missfires and flashing the check engine light. Most people ignore the flashing light and keep driving anyway.
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I'm wondering now about my upstream cat. My exhaust from the 3.4L V6 goes into a Y collector, an upstream cat, by an AFR sensor, thru a downstream cat, and then by the O2 sensor. I'm not sure how to check the upstream cat or how it affects the AFR and it's adjustment of tuning.
The repeated P0136 codes have worn me down. I just replaced the O2 sensor with a new Denso 234-4189. I erased the codes, a current P0136 and a pending P0136, and now I'll see what happens. While I was at it, I disconnected the pipe from the back of the second catalytic converter and looked in the downstream side of it. It looked perfect and clean. I'm hoping the O2 sensor, having 254k miles on it, was the problem all along.
brillo_76
Elite Member
Mostly us as the heater circuit burns open when they get old.
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