This is on a normally aspirated car and the CEL just came on and has stayed on. We did have it come on about a month ago while driving over a mountain pass over 9000ft but it went off again.
The car lives at 5000ft normally and has to get over the pass every few weeks when my daughter comes home from college
The code description says "Fuel Trim Malfunction (A/F too Rich).
I can understand that air is thin at 9000ft and could cause a rich mix, but i would have expected the computer to adjust for this.
The guy at O'Reilly who read it said the O2 sensor may be blocked.
Assume he meant the upstream one
Has any forum member had a similar problem and can give me some advise on what the fix might be?
many thanks
Ian