Honda Civic 99 gx electrical problem please help

okay so I have a Honda Civic 99 GX Natural
Gas and recently I moved to California from
Utah and I live about 50 miles away from the
nearest CNG  station and recently on the
way to get gas my speedometer stopped
working my battery light came on and my
check engine light came on so I went to a
mechanic and both of my O2 sensors
tripped and my speed sensor as well he
cleared them and I drove back home no
problems a week later I drove back to get
gas and the lights came back on and the
speedometer tripped a couple more times
any suggestions or ideas on how to solve
this problem I have looked at my
connections to the speed sensor in it seems
to be good my ground has a good
connection everything else works fine
please help