On earlier models (I have an 89 P-U) you have to move a screw on the back of
your instrument cluster.
There should be a screw hole identified as "KSW-A" and "KSW-B". "A" is below a
ground terminal/screw and "B" is over to
the right with a piece of masking tape over it. Every 90,000 miles you have to
move the screw from one position to the
other (if the vehicle runs OK, changing the O2 sensor itself isn't needed) .
Hope this helps.
| I just replaced the oxygen sensor in my 95 Isuzu Rodeo after the O2 trouble
| light on my dash lit up. Having replaced the sensor, the trouble light has
| not turned off. I was told that it has to be manually reset. However, I
| can't find anything in my Chilton manual about that. Any advice? (For the
| record, I have a limited amount of knowledge about auto mechanics, but look
| forward to getting better at it.) Thanks.