From time to time, there are comments about check engine light
problems. I have been one of those commenting, since I have had such
problems from time to time during the three years I have had my 900 SE.
The history of my problems dates back to just after I bought the car.
The check engine light came on, and stayed on, after I had owned the car
for about four months. I took the car to the dealer on several
occasions, and different solutions were tried -- including replacing the
oxygen sensor on a trial basis. Ultimately the dealer said the problem
was in the wiring, and resoldered some harness. That took care of the
problem for about 18 months.
Then, once again, a few months back the light came on as I was
driving. No driveability problems. I took the car to an independent
Saab specialist, who said the computer indicated a vaccuum leak, and
this likely was a defect in the gas cap seal. I said that during the
earlier round of problems I had had the gas cap tested at an emissions
testing station, and they said it was fine. The independent mechanic
said the testing station's standards weren't high. So I replaced the
cap, and the problem went away again.
Third round of problems. (Wake up, you at the back of the room!)
Started about a month ago, when I drove off from a gas station without
having put the gas cap on. I noticed the problem soon afterwards, went
back to the gas station to retrieve the cap, and the check engine light
came on as I was returning to the gas station. The gas cap had been
crushed by another car, so I bought a new one. The check engine light
went off again after about 20 miles after I had put the new one on.
However, on a long trip about a week ago, it came back on again -- for
no apparent reason -- and stayed on. I've been driving around with the
light on, intending to get it seen to when I had a chance. HOWEVER,
yesterday, on a whim I unscrewed the (relatively new) gas cap, and
screwed it back on again. The light then went out and stayed out.
Can anyone diagnose this problem? I'm wondering if, going back to the
first occurrence, it was ALWAYS a gas cap problem, although that doesn't
explain why the check engine light came on again after a new gas cap had
been put on. I very much doubt that it was because I didn't screw the
cap on sufficiently tightly at my last fillup. Despite my negligence in
leaving off the cap that one time, I am usually meticulous about this
since I found about the link to the check engine light. Furthermore,
the time the light came on on my long trip, I had driven about 200 miles
since the last fillup. So it couldn't then have been because I didn't
properly secure the cap after filling up the car.
Secondly, since the car has 83,000 miles on it, it's likely soon to
need a new oxygen sensor. Do I really need to pay $400 for this part
(which is what the Saab specialist told me they cost). Also, is putting
in a new O2 sensor an easy DIY job?