I normally run premium Costco 91 octane alcohol free fuel for the LeSabre. Although the 3.8 was engineered to run on 10% ethanol and you can run it on 87 octane, I like the added fuel mileage and theoretical higher detergent levels of the premium fuel. I basically run this all year long and then once a year, I run 10% ethanol Regular grade Costco to absorb any moisture that might have collected in the fuel tank over the last year. I did this last week and about two days afterward I got a flashing check engine light that then turned solid while I was heading back home. The car did not strand me but has a slightly rougher idle and acceleration from a standstill and is a little sluggish off of the line until she gets going. It is easy to notice because this car has a wonderful torque curve and a remarkable smoothness about it befitting to a car with the Buick name on it. I decided that the time has finally come for me to order my own OBD II reader and so I have one of those Bluetooth “BLUE DRIVER”s being shipped to me and I should have it by Monday. I suppose my question is do you think switching from a years worth of premium back to 87 would have caused this since I know the car’s computer is designed to adjust for different octane levels. Or maybe it is just a random thing and the OBD reader will give me more info if I need to replace something like a MAP sensor etc. Notice in the photo I attached here with all of the dash functions that everything has been operating normally. When I first saw the light, my first instinct was to look at my dash readings and everything looked fine including oil pressure, temperature, RPMs etc. could be that the car’s computer is giving me a heads up that something needs adjusting or replacing? Does anyone have any theories as to what it could be? I guess that’s a loaded question and it could be just about anything? FYI, I am the second owner of a soon to be 23-year-old car that has been treated like royalty all its life and gets quite a few offers whenever I take it to get any kind of service. With only 90,000 miles on the odometer, your girl should have quite a few years left in her. I am not a senior citizen but I i’ve always driven like one so there’s that too.
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