Here's some potentially helpful information from https://www.obd-codes.com/p0101
Basically, this says: look for vacuum leaks and examine the wiring harness.
Possible diagnostic and repair steps include:
* Visually inspect all MAF sensor wiring and connectors to make sure they are intact, not frayed, broken, routed too close to ignition wires/coils, relays, motors, etc.
* Visually inspect for any obvious air leaks in the air intake system Visually *closely* inspect the MAF sensor wires or film to see if you can see contamination such as dirt, dust, oil, etc.
* If the air filter is dirty, replace it
* Carefully clean the MAF using MAF cleaner spray is generally a good DIY friendly diagnostic/repair step
* If the air intake system has a mesh in it, make sure that is also clean (VWs mainly)
* Loss of vacuum to the MAP sensor can trigger this DTC
* A low minimum air rate through the sensor bore may cause this DTC to set at idle or during deceleration. Inspect for any vacuum leaks downstream of the MAF sensor.
* Use a scan tool to monitor real-time sensor values from the MAF sensor, O2 sensors, etc.
* Check for Technical Service Bulletins (TSBs) for your particular make/model in case of known issues on your vehicle
* The barometric pressure (BARO) that is used in order to calculate the predicted MAF value is initially based on the MAP sensor at key ON.
* A high resistance on the ground circuit of the MAP sensor can cause this DTC to set
* Do an exhaust backpressure test to determine if the catalytic converter may be clogged