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My O2 sensors have been doing this same thing for 4 years. I reset the ECU by disconnecting and discharging the capacitors the same way you outlined in your post. It will also reset them if you connect the negative termial last after removing both, IIRC.

I reset the ECU when the traction lights pop on after a hundred miles or so. They stay off until the next rain storm or I go mudding in deep water. Benn doing this a few years.

Had to do the CV/axles this week, so getting the lower O2 sensors replaced as well - both have 333K miles, so might as well.
 

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P0420/P0430 Catalyst below efficiency below threshold Bank 1/2 can often be caused by just an exhaust leak. The correct Toyota procedure to reset the ECM without an OBDII tool is to simply disconnect the negative battery terminal for at least 2 min. Sometimes when you reset the computer this way with dirty/aging sensors the ECM can't tune itself back to where it was and you can get some codes this way. You are on the right track though, Check for exhaust leaks, clean the MAF and TB, replace the air filter, check your plugs and run some heavy duty fuel injection cleaner/Techron through it as the first step. Then replace the rear 02 sensor for Bank 1 and if it still comes back replace both upstream 02 Sensors as a pair. I usually consider the upstream sensors as tune up items at 150-200k miles depending on condition (I like rehabbing high mileage Toyota/Lexus as play toys), even if you aren't having a problem with them they can greatly affect fuel economy if replaced with high mileage as they are not reading accurately anymore. Your fuel trims can give you an idea of how well tuned the engine is. All of the things mentioned would give you a decent tuneup if you took care of them. There is supposed to be an additive cleaner for them buy I have never tried that and just replace them to start over with fresh OEM Densos.

If it is just a traction control popping on you need a better tool to scan the ABS/TRAC computer to pull the codes. Wheel speed sensors codes are a fairly common ABS/TRAC issues, either the sensor, the wire or the ring on the shaft can cause problem. Sometimes aftermarket/reman CV's can have the wrong ring or have it out of position a little and cause the problem. Wheel speed sensors usually also cause the CEL by also throwing a C1201 code. The other common issue for just the TRAC/ABS and 4x4 are the transfer case actuators.
Gotta get the codes read to start though.
 
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