LS Engine Swap 95 to 96 now getting codes

[markquila]

Hello -

My daughter totaled her 95 so we found a 96 and put the much lower mile engine in. Engine runs fabulous just like in the other car. After a few hours of running, the engine light comes on. Nether LS had codes before the swap Checked codes and get these: "PO450 Evaporative Emission System Pressure Sensor Sensor/ Switch" and "PO430 Catalyst System Efficiency Below Threshold Bank 2". . 

What I could find on out there was limited but I believe the 96 had an emission system that the 95 did not. I still have the 95 as a parts car so looking for best options to turn the engine light off for these errors. Again, engine runs fine and she is driving it every day. 

Thanks in advance for any assistance. 

Mark 

[billydpowell]

My 99 has 230++ and I got the "bad cat" note.. I found a 2000 ls, hit in the side with 117k, and bought the cats from him for 135$ shipped to Dallas, put them on and no more problems, that was last December... 

[vissine]

I think this problem is more like electrical connections. 

[markquila]

Thanks visine. Where on earth do I start to troubleshoot this issue to clear the code for good? I can clear codes but it comes back after few hours of running. 

Thanks again!