Hello all - this morning about 30 mins or so into my drive to work, going pretty fast on highway, I noticed my CEL started blinking slowly. It would do about 11 slow blinks, then do nothing. It did this maybe 2 or 3 times, and then stopped / has not done anything since. Engine temp seemed normal, oil pressure seems normal to me, I re-did the gas cap after getting to work (I did get gas yesterday, but at the same place I always get it). The alternator was replaced about 2 weeks ago under warranty by the dealership. What'* strange to me, is that I drove it to Autozone (by now the light had long been off), and used their tester tool, only to get nothing / no code.....isn't the code supposed to be stored into the computer?

Anyone have any input here?

The flashing check engine light indicates severe misfires that could damage the catalytic converter(*).

As for why it didn't store a code, I suspect enough mileage and/or drive cycles elapsed between the event and the scan.

That can erase old codes.

Well, it was only a few miles. I had probably 2-3 miles to the office when the light went off for good, and Autozone is literally 1.5 miles from my office. So we're literally talking about 3-5 miles between the light going off and me testing at Autozone.

I should have clarified. I didn't go to Autozone until my lunch which was a couple hours later, but we're talking about 3-5 miles between the light turning off and me testing at Autozone. I had probably 2-3 miles to the office when the light went off for good, and Autozone is literally 1.5 miles from my office.

If the PCM saw the problem resolve, and stay resolved for some predetermined distance, then the codes might have been dumped by the end of that drive cycle or during the next one.

There is also a chance that the Autozone person didn't look at historical codes.

How many miles on this vehicle?

It would just be a very quick turn around for all of that to happen - the light started blinking when I was very close to the office, and by the time I was there, no more blinking


As for the autozone person, they basically had no hand in it. They handed me the device, told me to plug it in, turn the keys to accessory (But no engine), then the machine will do its thing and tell you when it'* done. so i did exactly that, brought it inside, and here'* what the printout gave me
truck has about 67k miles

That makes sense. It is looking for active and pending codes. It doesn't mention historical codes.

Cool, this tells us that it probably doesn't need spark plugs yet, unless it has an egregious amount of idle hours like a police car.

If it were mine, I'd monitor for recurrence for a few hundred miles.