Hello
two days ago driving home I noticed my battery PID on my ktuner was reading 12.1v. When I turn on my lights or AC it goes to normal 13.9v 14.1v. Turn off lights sits 12.2v is the voltage regulator in the alternator going out or is it something else?

 

Yes, most likely voltage regulator.

 

Before you replace the alternator, google "Honda dual mode charging system" and make sure what you are seeing with your car is not by design.

 

The two modes can accomplish as much as 10% load reduction on the engine by allowing the Electric Control Module (ECM) to determine charging rates based on information gathered from an Electric Load Detector (ELD) and various other sensors. During heavy electrical or mechanical loads (i.e., if the AC clutch is engaged), the ECM will set the charging voltage to 14.4-14.9V (high output mode); during startup and light electrical load conditions, the ECM will set the charging voltage to 12.4-12.9V (low output mode). In the latter case this anomaly might cause a technician to try to diagnose a low charge problem, although it is normal to have 12.5-12.7 charging voltage when the parameters are met.

So the manual says 12.5 volts, which is much higher than 12.1 volts.