Check engine light flashed for 15 seconds and then turned off, did not come back on. Why?
Posted by holyredditbatman-_-@reddit | askcarguys | View on Reddit | 41 comments
So I was driving home from work when my check engine light began flashing. Engine was running smoothly and normally— no shaking or stuttering. Since I know the severity of a flashing check engine light, I immediately began the process of pulling over when the flashing stopped. I was only 10 minutes from home, so I continued home and parked.
About 20 minutes later I went back out and took the car for a quick drive. Took it on the freeway and got it up to 70 mph, no light came on. No issues with the automatic shut off at red lights. Light never came back on or flashed again. I made an appointment with my mechanic for Saturday (today is Monday). I’ve just never seen this. Literally nothing out of the ordinary other than the flashing itself. Car still starts right up and runs fine. Any idea what could have happened?
WatchHores@reddit
gas cap was not properly screed on. redo gas cap. will fix itaelf within a few days. something, aomething, pollution control systems.
right415@reddit
Gas cap doesn't cause flashing. Only catalyst damaging faults cause flashing
ShyGuytheWhite@reddit
Dead miss too
right415@reddit
A dead misfire damages the catalyst
ShyGuytheWhite@reddit
Depends on the dead miss. Clogged injector can't spray fuel can't damage the cat.
right415@reddit
When one fuel injector isn't firing, the oxygen sensor detects a lean condition due to unburned oxygen in the exhaust from the misfiring cylinder. In response, the engine control module (ECM) increases fuel delivery by enriching the mixture for all cylinders. This causes the short term fuel trim to rise as the ECM tries to compensate. The excessive rich condition in the remaining working cylinders overwhelms the catalyst. Do you have an ASE L1 and a SMOG license?
Potential_Stomach_10@reddit
And too many misfires
right415@reddit
Too many misfires damage the catalyst
ShyGuytheWhite@reddit
Flashing MIL is severe critical. Gas cap emission problem will just throw a solid MIL.
OGigachaod@reddit
Odd that it would go out if it was critical.
ShyGuytheWhite@reddit
Rare occasions still happen despite being rare. You could have something wiggle loose just enough for long enough to cause a problem and then when you shut something off it wiggles itself back into place. We call those things gremlins.
dirtydan442@reddit
Wouldn't cause a flashing CEL
OGigachaod@reddit
Yeah, there's a special light for gas cap :)
holyredditbatman-_-@reddit (OP)
No gas cap on this vehicle, just the little gas door
GetawayDriving@reddit
If a check engine light goes on for 15 seconds, and no one is around to see it, did it ever go on at all?
holyredditbatman-_-@reddit (OP)
lol that’s my general mindset but I just don’t love that it was blinking. Usually means a misfire, it just really didn’t feel like one
Turbosporto@reddit
When this happened to me, 5.4 F150 I had an intermittent misfire. Replaced spark plugs. Any repair shop can pull the codes for you.
holyredditbatman-_-@reddit (OP)
I’m assuming/hoping this is all it is. Got the appointment scheduled and hopefully can get done in a day
Turbosporto@reddit
You’ll be just fine. Good luck
holyredditbatman-_-@reddit (OP)
Thanks! Main concern is getting to Saturday
Bright_Crazy1015@reddit
Blinking CEL means pullover, now catastrophic failure imminent.
There's no other way for me to interpret that.
Did your ECM fail? Does the owners manual cover the behavior? Did you count the flashes? Is it repeatable?
Alarming-Contract-10@reddit
That's literally not what a blinking CEL means. It quite literally means what op said, current active misfire.
Con-vit@reddit
This is correct. To add to this, the active misfires can lead to catalyst failure due to unburnt fuel coating the cat and causing it to melt the substrate.
6ixseasonsandamovie@reddit
My car flashes the maintence light for about 30 seconds or less after turning the car on when its due for an oil change. As always you should check your manual
sovereignpancakes@reddit
Reiterating others' advice. Go to Advance/Autozone/Canadian Tire/whathaveyou and ask them to read the stored code. Look it up and see what you can find out. Then when you take it to your mechanic on Saturday you'll have an idea of what might be the case.
hamburgergerald@reddit
Could be a fluke. Could explode on your commute tomorrow. We shall see.
Bright_Crazy1015@reddit
Make model year would help. Along with conditions at the time. Highway use, city driving, sitting at a red light, etc.
Any codes or failures since? Does everything work as it should? Does the owners manual describe this behavior?
Hayburner80107@reddit
This is why you always have electrical tape in the glovebox.
redditsuckshardnowtf@reddit
RTFM
what_irish@reddit
“If it flashes, engine misfire may be occurring.Increased exhaust gas temperatures could damage the catalytic converter or other vehicle components.Drive in a moderate fashion (avoid heavy acceleration and deceleration) and have your vehicle immediately serviced.”
thzmand@reddit
Yes a flash is usually a generic misfire across many cars. Sometimes they really are intermittent, but you may be due for new plugs, cables, boots and possibly coilpacks to be really sure. Reading the codes will tell you what was stored and will point to your fix, but the above is a common scenario.
Caaznmnv@reddit
Put a good code reader on it. You can have something like a small misfire that doesn't fully trigger the check engine light. But if you look at code reader, it may show something like a level 1 of 3 misfire stored in the onboard diagnostic computer.
Pantology_Enthusiast@reddit
Probably a misfire or a failing wire.
Read the codes to find out.
holyredditbatman-_-@reddit (OP)
Oh this is also a 2022 Ford Ecosport
what_irish@reddit
Well there’s your problem. It’s an ecosport!
All jokes aside, in my experience when the check engine light flashes it’s an ignition system or timing issue. Too many misfires in a short period or a knock happened for some reason. Typically for me redoing the spark plugs and wires or getting the right octane rating into the tank fixes it. But your car is quite new so depending on miles I’d be a bit surprised if it was the ignition system.
The best thing you can do at this point is pull the codes and see a mechanic. But it also could’ve been a one and done issue. Air got into the system somewhere, a plug somewhere vibrated just right, you drove through the spirit of your enemies ancestors, who knows.
retardrabbit@reddit
Go get the codes read.
Since the light is off there won't be a current code, but there should be a (the same) history code stored and maybe a permanent code.
Have them print it out, write it down, or take a photo with your phone so that you have that available for reference.
Store your vehicle's VIN and license plate number in your phone for reference "hey Siri remember that my VIN is...." That's just good practice in general.
Then post again with that info
OGigachaod@reddit
Mine was on for 2 weeks and is off now, no idea, lol.
GoodResident2000@reddit
It’s time to LS swap it
right415@reddit
What's the code?
InfectiousPessimism@reddit
Go to somewhere like AutoZone (if it exists where you are) and have them scan your check engine codes. That'll tell you what possibly was happening when the light flashed.
I-r0ck@reddit
Your car didn’t like something it was reading. Probably a sensor that got blocked for a few seconds or something similar; it’s hard to know without reading the actual code.