Alright I just bought this car form a friend because he was tight on money, and gave me a good deal on it.
The car has active codes:
P0133B - O2 sensor b1 s1 slow response
P0171B - Bank 1 too lean
P0420 - Cat eff. below threshold (b1)
The car has aftermarket headers, up-pipe, and a cat back exhaust. Anyone know what it may be? I work at a Peterbuilt dealership and the guys there said its probably a faulty O2 sensor, but then again we work on diesel engines haha. So, some input form someone else with some exp. would be great.