Yes I use Torque Pro app on my Samsung Fascinate. The OBD2 code I get is P0420 and my car, I believe has the original catalyst. I bought it used with 40k miles and no modifications have been done by me. I haven't changed the sparkplugs (dealer wants around $200 to do it) and the car has around 170k miles now. Could this be it or part of the problem?

Read this thread:

https://www.gmforum.com/obd-ii-troub.../p0420-284086/

Probably a faulty O2 sensor.

changing the plugs isnt that bad, the stealer is always a rip off. you just have to have a few different lengths of extensions for the ones in the back. the regular 3800 likes delco platinums or e3. look on rock auto. i would do that first, clear the codes and see what happens. then if it comes back it might be o2 but since the cat is original its likely the issue. as long as there are no exhaust leaks. you have to get a good oem type cat to maintain emissions compliance in your state. rockauto probably has one of those too. if you dont want to do it yourself call around to a good rated local owned shop. they have much better prices and are much less likely to rip you off.

welcome!!!

Welcome to the forum Dwayne.

Dwayne Welcome to the forums!
My nephew just received his 01 LeSabre solid and good engines, just keep and eye on the upper and lower intake manifold gaskets. I keep an eye on the coolant reservoir to ensure I have no leaks...
I used Bosh Iridium Spark Plugs in my Pk Ave with 3.8 and it seems to really go and like them!

Not sure if he'll get the welcome guys, this thread was from last June.