I think you are saying banks 1&2 sensors are lean. That has nothing to do with the cats. A 96 is OBDII so you have a cat sensor. It would read a cat code like P0420, insufficient cat performance or HO21 out of spec. A lean code downstream means too much flow. An upstream lean code ( bank 1 & 2 ) is likely a vacuum leak. You borrow gauge from Autozone. What is the code you are getting.

 

that was the code it said insufficent exhaust flow it was flashing the cat symbol on the scanner it has 2 cats the truck just don't seem to have all the power on the hiway

 

Is the cat sensor behind the last cat then?

 

Usually the sensor is behind the first cat. Sometimes its after the second. Insufficient flow is the code your looking for then. However of could still be a leak in the headers or pipes. Cats can be expensive to replace so personally I would throw a gauge on there to verify. You can also disconnect the exhaust to see of that picks up your power but you will still have a check engine light and its a very subjective test. I prefer to deal with hard numbers myself.

 

So if I was to cut the exhaust off just in front of the cat and if it runs better then the cats would be bad? If it doesn't chande any what else could it be?

 

Don't cut anything just unbolt the pipes from the manifolds and let it hang while test driving, it won't drop much but will give you a big difference in power if they are clogged.

 

Thanks man!!

 

X2. Like I said it could be exhaust leaks or vacuum leaks or valve issues. We need to do more troubleshooting and need all the codes. I still highly recommend getting the right tools and testing it the right way.

 

Ok guys went and scanned the codes today and came up with these po136,po141 and po174 would a bad cat cause these?