Celica Forums General Discussion Engine and Performance CEL help?

I have a 2000 Celica GT-S with a good number of miles on it, and about a month ago my CEL came on. Car was running completely fine, I was doing about 90 on I-75. Ran the codes at Autozone, came back as P0171 Bank 1 System 2 Lean. I was told this wasn't an issue and would just make my mpg worse and should run without issue, but that stupid CEL light is driving me crazy.

I keep seeing that the easiest solution is to clean my MAF sensor? My friend is replacing my air filter (as well as my cabin filter which is missing!) and apparently that's the best time to do it, but I've read that it's really easy and costly to mess up you MAF filter. Should I just leave it or..? I don't really know much about cars and I really don't want to mess anything up.

I read the guide on how to clean it, I'm just wondering if it's worth it.

RE: Cabin air filter
Toyota didn't include them in the Celica until mid 2004, and only as a new vehicle "upgrade package option" or as a "recommended service" for an additional $52 part + cost of install. Since then, they have lowered the OEM part price, lowered the labor charge. In addition. several aftermarket brands are now available for around $16 USD.

As for the CEL, and for the routine maintenance which you're probably already doing a few times a year, check/clean your engine air filter.

Also, as you've also mentioned, clean your MAF sensor:
https://celicahobby.com/forums/ubbthreads.php/topics/67215/maf-sensor-how-to-clean.html

RE: P0171 Cehck Engine Light (Check Engine Light / Diagnostic Trouble Code Chart)
If you haven't done it within the past 5 years, or you often park outside under the hot sun, replaced your fuel cap. They can be had for about $12 USD. Your sensor may be getting a variable reading because your fuel cap has a slight leak and is making the A/F mixture inconsistent. After you replace your fuel cap, reset your ECU. Hopefully this resolves your CEL.