During a long highway trip, the check engine light came on in my VX twice. Both times, it was when I was on a long section of downhill, and was coasting in gear. I'm not sure exactly how long I was coasting, but it was at about the 1 mile mark both times (long sections of downhill in northern Oregon.)
Any ideas what would cause this? The light cleared immediately after restarting the car... no unusual symptoms. I was just wondering if this could be a sign of something *starting* to be a problem.
Mileage seems good, got in the high 40s on the trip (perhaps low for a VX, but I've had a pretty consistent average of 44mpg over the past 2 years.)
Even though the CEL went out, the code is still stored in the ECU.
Get the code by jumping the service connector terminals with a paper clip. It 's located by the passenger side front seat kick panel next to the glove box.
My guess is you triggered a code 48 LAF sensor. My first VX would do this under the conditions you described. I never noticed a driveability or mpg problem when the code 48 CEL turned on on either of my VX's. I guess the emissions potentially would not pass if the LAF sensor was lazy or clogged with something.