Have around 175,000 miles and car started sounding weird after check engine light and VSC light came on. I believe it gave us a P0042 code and we had a mechanic change it out and after driving a mile away the lights came back on and is now showing P0037, C1201, and B1400 codes. Humming noise when driving is getting louder as if the car is driving in a lower gear. I thought it sounded like back pressure buts it getting louder so not sure if it's transmission related. 

The C1201 code says it's disabled the VSC and the B1400 says something about power window relay but no known issues with the windows.

Should we have the transmission checked or should we replace the sensor to see if that fixes the engine sounding like it's running in a higher RPM but it's not.

Thanks

Scott Guinn