P0136 returning after changing cats and O2 sensors

I have code p0136 and I replaced both my catalytic converters and both my O2 sensors and unhook the battery and hooked it back up to reset the check engine light and it just came on again with the same code again what else could be the problem

 

I'm no expert, but my best guess would be the wiring going to the o2 sensor (I think the 2nd one) is bad. Maybe try checking for exposed wires?

 

When I had this code a new rear O2 sensor solved it.

Did you use a Denso sensor or something aftermarket? Aftermarket sensors do not play well with Toyotas

 

Remember it is the complete circuit not just the sensor in the heater circuit it comes down to a bad new sensor ?? Damage to the plug or harness or maybe the ECM

All the heater does is bring the O2 sensor up to operating temp on the cold engine.

As it is the heater part of the O2 sensor save your old cats most likely nothing wrong

 

can this be any reason why my check engine light p0136 is on?
my friend said it's not.
because he said it's wellded good.
So i was thinking it's because the one pipe is smaller going into the bigger one,s it not be getting the correct pressure.
I don't know anything about welding but I think it looks like a crappy job

 

Yeeeeah I would have an exhaust shop cut that and reweld it properly. That looks like ass lol

 

LMFAO he's giving himself waayyyyyy too much credit. High temp JB weld would work better than that

 

That looks like someone's first attempt at stick welding.

 

While the weld is rather poor that will not cause the code you have if indeed it is PO136

Just where it is located could cause a PO420 if it is between the 2 sensors

 

true, his issue is either with the sensor itself or the wiring.

Still not sure what kind of new sensor he put in, if it's an aftermarket brand (not Denso) then I would put a Denso one in first before trying anything else

 

The onboard diagnostic (OBD) code P0136 is defined as an Oxygen Sensor Circuit Low.
That tells me you probably have a wiring issue. Crt low means there is a short or voltage drop. A hi crt code would be an open crt.

 

It's after the 02 sensors

 

It used to be code p0420 until I replaced both of my catalytic converters.
Now it's p0136

 

In that case you have either a bad sensor it can happen with any new part.

A poor connection or damage to the wires

 

Thanks for the laugh