I still suspect this was a software glitch where the the code got stuck in E85 mode. The only sensor involved in this process is the O2 sensor. Not planning on using more E85 any time soon so probably will never find out for sure.
I live in western Michigan and there are a decent number of E85 station around. Generally, using E85 doesn't make sense. E85 has about 30% less energy per gallon compared to regular gasoline. Here in MI, fuel prices fluctuate wildly so, if you pay attention to the price spread, you can come out ahead some once in a while but typically it is not worth the trouble.
Many sensors in autos have lots of hysteresis built in to prevent "chattering." A common example is if you don't fully seat the fuel filler cap. This will (after a while) trip the "check engine" telltale. If you are hip to this behavior, you check the cap and tighten it. It can take DAYS or WEEKS before the telltale goes off! I suspect your E85 problem was an exaggerated instance of this behavior. BTW, living in the South, I am not exposed to any stations selling E85. Do any still sell it? I often wonder (when stuck in traffic behind a vehicle with a "Flex Fuel" badge) how much that "feature" actually cost, and how much benefit the driver got from it?
I have a 2005 Taurus and a couple of years ago I took the plunge and tried using E85 fuel. The owners manual says it is Ok and I confirmed from my VIN number that I have a Flex Fuel engine.
I ran a tank full of E85 with so so results so I decided to go back to "regular" fuel.
Soon after switching back, I began to notice poor performance. Reduced acceleration, rough idle and recurring check engine light. The engine trouble code was for fuel trim out of range. Basically, the engine was running rich but the ECM thought it was too lean.
I spend a couple of weeks trying to figure this out but just did not connect the dots to the E85 fuel. Then, I needed some serious work done, i.e. Torque converter shaft failure.
When I got it to the shop, I also asked them to investigate the engine code. When they called to tell me the work was done, I asked about the code. They said there were none! It has been running fine ever since.
It appears that the ECM detected the E85 just fine but could not detect that I had switched back. My Taurus needed an extended disconnect from the battery to reboot the ECM.
Was it a bad ground? or just part of the system that had failed? Probably the CD function is a separate code module since a remote CD chnger is often an option. So it is quite reasonable that just one area needed the re-boot sequence.
Now just think about the potential grief we would have if that mid-eighties dream od all those modules talking on one bus in the car. Just imagine the communications problems that could occur. But they went to one major module, although some have several, because of the high cost of so many modules, which was way more than the cost of the wiring saved.
This is all done in the name of "theft protection." However, at least in the case of radio/NAV head units, there is usually a way via the OBD II port to re-initailize and set a new passcode. You'd be astounded to learn how much of this there is in newer vehicles, all in an attempt to make theft of components (or the car itself) more trouble for the thief than it's worth. In some makes, it has gotten to the point that the "theft prevention" stuff is the least reliable subsystem of the vehicle, specifically designed with failure modes that disable all or part of the vehicle! And of course it adds to the cost as well.... and no, I can't turn this into a "Designed by Monkeys" article without breaking confidentiality agreements!
I am on my second Chevy Volt. Lots of electronics and lots of code. Things get weird at times (Like compass not working, GPS lost, ...) With this car, you can call OnStar to do a remote diagnostic as you are driving. Both in the 2012 model and 2013 model, running this remote diagnostic seems to reset some systems and make things work again.
Again, good intentions, but at risk for practical use. Consider an older car that's sitting on a used car lot and the Owner's manual has been long since-misplaced by a previous owner. You suggested it's up to the owner to keep it safe, but Manufacturers can't count on an owner behaving responsibly.
Back to the point of the article; a complete electrical shut-down (power-down; re-boot) really should be all that is required to reset electronics. It's logical -- Why make it more difficult-?
Not crazy. The code is supplied with the vehicle/radio, and it's up to the owner to keep it in a safe place and transfer it when the vehicle is sold. My previous car was fitted with such a radio, when the battery needed replacing the service technician connected the car to a temporary "power cart" to prevent powering down the car completely. The setup will hold from capacitor charge for a couple of minutes, anyway.
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