Hey Scotty
I have a 2012 Nissan Sentra SER Spec V 2.5L 6speed manual,150000 kms.Check engine light came on.I have a P0101 code,MAF or VAF A Circuit Range/Performance.Is it something to be concerned about? Car runs fine with no issues.But I do hear a little rattling noise coming from underneath the car.Can it be the Catalytic Converter?
For the full list of causes, see here -
https://www.autocodes.com/p0101_nissan.html
Don’t forget to read the TSB that’s applicable for your particular vehicle.
For the noise/s -
All the best!
The rattling noise I would bet is the heat shield surrounding your cat
Should have nothing to do with your CEL
P0101 means your mass airflow sensor isn't functioning correctly, most likely it's just dirty. Get yourself some CRC maf sensor and throttle body cleaner and clean them, hundreds of videos on YT. Might as well do the throttle body (butterfly valve) too since it's right next to the maf sensor anyway. You'll need a qtip to clean the maf sensor and a rag (I use an old sock over my hand) for the throttle body valve
You should not touch the MAF sensor wires with a qtip or anything. Just spray it clean and let it dry.