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"NOTE: At this point it is worth noting on my GT (2000) the sensor wires were Nickel Alloy and solder would not take to them no matter how hot the iron! I made a physical connection by wrapping the resistor lead around the stripped wire. The solder adhering to the component leg made a good physical connection but did not truly stick to the wire!"
You need the right flux for that. I had no problem with "Bridgit" Burn resistant soldering flux. The solder flowed fine and made an excellent joint.
 

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Use barrel crimp

I used barrel crimps instead of solder. In fact Denso includes barrel crimps with replacement sensors.

They work OK both inside and outside of the car near the CAT. Just tape them up carefully to avoid moisture to creep in and do damages in long term.

"NOTE: At this point it is worth noting on my GT (2000) the sensor wires were Nickel Alloy and solder would not take to them no matter how hot the iron! I made a physical connection by wrapping the resistor lead around the stripped wire. The solder adhering to the component leg made a good physical connection but did not truly stick to the wire!"
You need the right flux for that. I had no problem with "Bridgit" Burn resistant soldering flux. The solder flowed fine and made an excellent joint.
 

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Tried MIL eliminator mod, now I have PO136 code

I did this mod two years ago to pass smog. It worked like a charm for about 1,000 miles (it may have only been 500 miles, I forgot), then I got code PO136 - Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2). That code came back every 30-40 miles when I'd clear it so I eventually left it alone.

Initially it kept my CEL off long enough to pass last time and that was my main concern but now I gotta pass smog again. Any ideas what to do?
 

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The electrical connections may be bad, adding resistance to the line, causing a drop in voltage.

Redo the connections by soldering or crimping.



I did this mod two years ago to pass smog. It worked like a charm for about 1,000 miles (it may have only been 500 miles, I forgot), then I got code PO136 - Oxygen O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2). That code came back every 30-40 miles when I'd clear it so I eventually left it alone.

Initially it kept my CEL off long enough to pass last time and that was my main concern but now I gotta pass smog again. Any ideas what to do?
 

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The electrical connections may be bad, adding resistance to the line, causing a drop in voltage.

Redo the connections by soldering or crimping.
I already have them soldered, but I'm not that good at it so I'll try again. I'll replace the resistor too. I missed an earlier post that said they can go bad if you overheat them while soldering.

Also, I just googled PO136 last time and copied/pasted that bit about low voltage, but that was for another make/model apparently. For Toyotas, PO136 is: "O2 Sensor Circuit Malfunction (Bank #1 Sensor #2)" so not necessarily low voltage. I'll still resolder and put a new resistor on, but any idea what else it could be if that's not it?
 

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For Toyotas, PO136 is: "O2 Sensor Circuit Malfunction (Bank #1 Sensor #2)" so not necessarily low voltage. I'll still resolder and put a new resistor on, but any idea what else it could be if that's not it?
Rodents eating the wire/insulation caused this code on a Prius I helped work on.

Here are two of the OP images enlarged; for some reason they are the thumbnail versions in the first post.



If someone has this issue elsewhere, you can replace the word "thumb" in the image URL with "medium" to see a less microscopic version.

I may have to do this mod as I got P0420 recently. I cleared it, just in case it's related to my recent overhaul. I doubt it, but with my inexperience...

Anyway, I look forward to cutting and soldering some wires.
 

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The ECU sees the O2 sensor bank 1 sensor 2, after the CAT as not working.

The O2 sensor could be dead. It could be the R C values, or their solder connections, cause low voltage levels on the signal sent to the ECU.

check the R C and the solder joints for any damages. Replace the RC and redo the solder joints if neceessary.

If that still fails, test the O2 sensor for voltage output.

I already have them soldered, but I'm not that good at it so I'll try again. I'll replace the resistor too. I missed an earlier post that said they can go bad if you overheat them while soldering.

Also, I just googled PO136 last time and copied/pasted that bit about low voltage, but that was for another make/model apparently. For Toyotas, PO136 is: "O2 Sensor Circuit Malfunction (Bank #1 Sensor #2)" so not necessarily low voltage. I'll still resolder and put a new resistor on, but any idea what else it could be if that's not it?
 

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This RC fix will not work on V6 engines.

A double extension added to the aft O2 sensor will work immediately, eliminating CEL PO420, but not sure how long it will last.

The ECU sees the O2 sensor bank 1 sensor 2, after the CAT as not working.

The O2 sensor could be dead. It could be the R C values, or their solder connections, cause low voltage levels on the signal sent to the ECU.

check the R C and the solder joints for any damages. Replace the RC and redo the solder joints if neceessary.

If that still fails, test the O2 sensor for voltage output.
 

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Actually, the PCM is looking for a rich condition after the cat and slow (if any) cross counts. The catalytic converter uses left over fuel and heat, combined with available oxygen to further complete the combustion process and produce carbon dioxide and water. This will show as a rich condition or about .6-.7 volts pretty steady on a rear o2 sensor. Also, an o2 sensor actually measures the absence of oxygen, so calling it a "rich" condition is kind of a misstatement (as it actually just means lack of oxygen, not necessarily excess fuel) but that's what the tech community calls it.

Source: CA Smog Tech.
 

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Adding this RC network to the O2 Sensor 2 line will reduce the frequency of high O2 level in the exhaust gas at the sensor 2, therefore fooling the ECU into thinking the CAT is working perfectly.

It seems to work for 4-cylinder engines. I tried it on V6 engines in Lexus and Mitsubishi cars and it did not work.

A simpler fix would be to add a spark plug extension to the O2 Sensor 2 so it sees less Oxygen in the exhaust. You can buy the plug extensions in any part stores.
 

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What if there is no where to bolt the sensor in? The previous owner plugged and welded the o2 bung.
I have everything required to make a complete eliminator, but I'm not sure how everything should interconnect.
 

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Nice write up and follow ups. If anything, your simple breakdown helps us to understand how our cars work. As you have stated in the beginning, this is for informative purposes only. But it's always nice to see what can be done withour cars. This is 2018, and this car still looks great next to some of these modern cars. It's amazing how other owners have really modified their cars to make it their own. That's why i'm always here, to find out what works and what doesn't work. Thanks members for sharing your ideas!!
 
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