I have an OBD1 code 157 MAF under voltage expected.... and I don't know what to do. Can anyone please help?
Thanks!

 

Have you pulled the sensor off and cleaned it? If not pick up some electrical contact cleaner and clean it. If that doesn't help, you may need to replace it.. or the wire that connects to it

 

No, don't use electrical contact cleaner, use only MAF sensor cleaner. Never touch the MAF sensor electrodes with anything. Let the stream of spray do the job. Make sure the harness connector is o.k.
If this doesn't work replacing the maf sensor makes sense.