Here are the details, I have a 1993 Trooper S, manual tranny, with
118K on it. I have never replaced the O2 sensor, even when the light
went on at 90K. Gas mileage seemed fine and no other lights came on.
It just went on for its 120K services and tune at the dealer (I just
moved here and did not know a good shop). Prior to this service I had
done everything the manual said regarding service (oil changes, tires,
60K and 90K services, etc). I did notice some decreased fuel
efficiency at 110K and I asked one dealer mechanic if I should
replace the O2 sensor now (thinking decreased fuel efficiency was sign
a sign the O2 sensor finally was shot). His response was only if the
O2 light AND the check engine light were on simultaneously - otherwise
the O2 sensor is fine. Just for kicks, I asked another dealer
mechanic 3 bays down from the first, and he said it was likely fine
and that the decreased fuel efficiency was a sign that I needed a tune
up and not a new O2 sensor. I opted for a 120K tune-up, in addition
to the 120K service, and they said they would check and reset the O2
sensor instead (replacing it only if needed). When I picked it up the
O2 light stills comes on and they did not mention checking the actual
sensor (it was late and I was in a rush to get home). However, the
car drives great and fuel efficiency *seems*
better - but it is early
to tell as I have only driven 50mi on it since I picked it up.
Which one of these mechanics is right - or is there a different answer
altogether regarding O2 sensors. I am curious as I am getting ready
to drive from the Midwest to Yellowstone for summer fieldwork and I
would like to use as little gas as possible. I do have a couple of
days if I need to get a new O2 sensor, but that's it.
Thanks in advance for your help ...
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