We have here a 1990 RRC 3.9i GCC spec (low tech, no code display)
Have no Owners manual to read what this means.
We are talking here about the light with the exclamation mark and yellow/amber colour.
Had the same light before and disconnecting the battery solved the issue for a while, but now its back...
The light came up again a few times and I just reset all by diconnecting the negative on the battery.
BTW this model is not equipped with cats therefore no o2 sensors!
today something new came up - the light got on while driving. was standing at a traffic light and felt some light vibrations from the engine and right after than I recognised the light (of doom)
what would be your next guess to check??