Well, it is summer, which means it is time for the return of the sporadic CEL on my 2000 Honda Accord. Typically it will come on, and then go out 60-80 miles later (presumably when it goes through the next cycle). If I get the codes pulled, it’s typically either P0170 or P0172 (sometimes both). Most of the time when the CEL comes on, it is right after filling up, or it’s when the tank gets down between 1/8 and 1/4 tank.
And it only happens during the summer. It will first pop up in late May or early June, and will typically pop up every few days during the summer, and is last seen sometime in September (last year, it happened once in October). The only thing I can figure is that something about the summer gas formulation (which, according to what I can find, is roughly Jun 1 to Sep 15) puts something in the car right at the ‘edge’, and occasionally it pops over to a range which turns on the CEL.
This doesn’t appear to affect how the car runs, it just induces some anxiety in the driver every time it pops on. The plugs were changed last November, and I’d hoped that might deal with this, but it’s baaaaack! Anyone want to take a stab at what the summer formulation might be affecting to produce this?