SLEEK00SS

P0171 Fuel Trim, Bank1, System too lean. Anyone know what this might be? I'm hoping it's just an O2 sensor or something stupid. I just hooked up my Air/Fuel Ratio guage to the left front O2 sensor. It just came on last week and I cleared out the code. Any help would be greatly appreciated!

SLEEK00SS

Now "P0430 Catalyst Sys Efficiency Below Threshold (Bank 2)" code set. Anyone have any ideas please?

TXNC5

How and where did you tie into the front O2 sensor? The GM manuals recommend to never tap into them. I have read where some people were successful in doing so, but they made sure that they used the appropriate wire and soldered their connections. Otherwise, you can affect the voltage output and thus create codes. You will want to check for all possible leaks after the MAF, vacuum leaks, and exhaust leaks. Depending on how/where you tied into your O2 sensor, you could try swapping the two front O2's to see if the code moves with the O2 sensor or stays.

The 430 code might indicate an actual problem with the passenger side cat. I don't have cats, so I don't have any insight there. If you have a scanner and a WB, it would be good to see some detailed info of all the oxygen sensor activity and the actual A/F.

Here is a detailed description of the P0430.

Here is a detailed description of the P0171

SLEEK00SS

I didn't actually tap into the wires. I used the GM pigtail tap that LMPerformance sells to hook up the guage. No cutting or splicing.

SLEEK00SS

I erased P0430 code and came right back on again within an hour or 2.