Catalytic Converter OC Thermo Sensor Help!

[djawahir]

I'm trying to figure out if the thermo sensor on my cat is bad. Right now, when I put the ohmmeter on the plug terminals under the center console as stated in the emissions manual, I read 'open'. For a good thermo sensor, it should read between 2-200kohm according to the manual.

But here's a question that I don't think anyone has asked about the thermosensor. When the cat temperature goes up, does the thermo sensor read less than 2-200kohm? Or does it read more than 2-200kohm?

I may get flamed for this, but there's good reason for this question and I may be able to get around paying $200 for a new thermo sensor.

Does anyone have the temperature curve for this thermo sensor?

 

[pismojim]

It sounds like the resistance decreases to close the circuit when the cat gets too hot. Just guessing, I don't have my manual.

I accidentally cut my sensor during a cat swap a few years ago. I meant to replace it with a used one off a similar vintage toyota but never got around to it. Everything seems fine without it. No effect on passing smog tests.

IIRC it cuts off air injection into exhaust if the cat over heats. I doubt it's much of an issue especially with a newer aftermarket cat or well tuned motor.

In my opinion, don't worry about it or find a used one. Spend the money on a tune up and new aftermarket cat.

 

[NocalFJ60]

https://forum.ih8mud.com/showthread.php?t=38627

https://forum.ih8mud.com/showthread.php?t=25907

Pull the sensor out and put a propane torch on it and the resistance will go down as it gets hotter. Mine was reading open to until it got really hot.