86 jetta gli O2 sensor light

the O2 sensor light in my 86 jetta is coming on sometimes when i start it up ill drive it for a few miles an it will go off what could be causing this?.... any ideas will help thanks

the O2 sensor light in my 86 jetta is coming on sometimes when i start it up ill drive it for a few miles an it will go off what could be causing this?.... any ideas will help thanks

...is this the same '86 Jetta that you've posted 'overheating problem' ???
if the same, the cat may be clogged, causing an O2 light; AND also the overheat condition...

ctesla