Code p0420 could be o2 sensor??????

I got this code that poped up on my truck it means catylistic efficientce below threshold bank 1 what does that code mean could it be a bad up stream o2 sensor??

 

It could be a bad a/f sensor, cat or o2 sensor can't tell for sure without a road test and recording live data

 

This.

I had the P0430 pop up on my truck. Plugged my scan tool at work in and watched the live a/f & o2 sensor data, both sensors were good so I know I need a new catalytic convertor. I can't really afford it right now, so I just cleared the code and I it's been about 1 month and the code hasn't come back yet. Keeping my fingers crossed for now.

I have a friend at work who had the same code come up on his 04 taco. He cleared the code out 1 year ago and it hasn't come back. So my suggestion is to clear the code and see if it comes back.

 

Iv cleared the code about 6 times nd it just pops up about 15 to 45 miles down the road again

 

yea i just had this code pop up today also
i guess ill go through the list of fixes this weekend and see if i cant get rid of the light

 

A small exhaust leak can cause that code.

 

Does it matter where the exhuast leak is in the exhaust cuz soon as I cut my muffler off and put a piece of pipe in there is when it first started coming on so that would make sense

 

90% chance its the cat on the passenger side (B1). Check the sensors for leaks. Are your sensors held in by two nuts or screw in? The ones held in by the 2 nuts are vert common to leak, giving the sensor false readings.

 

my dad's 02 just had this code. He wound up replacing the converter.

 

In a simple answer, yes.

With more info here:
As mentioned P0420 is for catalytic low efficiency. The computer compares the pre-cat O2 Sensor data to the Post-cat O2 sensor. So if either sensor is bad, yes, it could cause a false P0420 code to set.

 

i finaly figured out what my proplem was when i cut my muffler off and welded in a piece of pipe i lossened the two bolts that conect the tailpipe muffler section to the cat section and when i was done i only tighened one of the 2 bolts so there was a exhuast leak and that was causing the light to come on

thank the lord for my stupidity