Flashing Check Engine Light help

Hey OP!
New to the forum! My Tacoma started experiencing exact symptoms tonight.
I’ve owned the truck for 5yrs now and have babied the crap out of it. Bought with high miles,266k (I’m 2nd owner, lady before me was in sales) truck is very good shape, nothing major has ever been wrong with the truck. So I’ve put about 35k miles on it in 5 yrs and been religious about maintenance. One of the first things I done to the truck was replace all plugs and coil packs. Plugs were OEM NGK’s, coil packs - eBay aftermarket. About a yr into the coil packs, had misfire code, put original back in and ran fine until now. I have a flashing CEL and no code on my scan gauge. I’ve always ran seafoam In my tank at least once a mth. So I’m leaning towards coils being bad. I’m gonna pull out the non OEM coils and put the originals back in to see if that fixes my problem. Sorry for the long post, What’s the verdict with yours??

 

Ultimately my solution was a new coil and new plug. Worked like a charm. Make sure you clear the codes too.

 

One word of experience here. I"ve been doing mechanical work for 45 years, everything from engine rebuilds to oil changes. One thing to be aware of is that new parts are not always good. The list of brand new items that I have found that were bad right of the box is LONG...: ignition switches, thermostats, throw out bearings, MAP sensors, U-joints, ignition condensers (that shows you how long I've been doing this), and the list goes on and on.

The lesson here: When trying to track down an illusive problem, it is possible that the new part you swap is also bad! If you swap in a new part and the problem remains, or is same but different, then try testing it another way. In this case try putting the suspected coil on another cylinder. Until I realized this, I spent long hours chasing my tail, only to end up back where I thought the problem was to begin with. The most epic fail was a thermostat replacement on a 1976 Ford. I had to return the thermostat to NAPA TWICE, and the third one was good. I bought a new Spicer u-joint years ago and the inside of one cap was not machined! It happens more that most realize. Now I test / inspect new items as well as I can before I install them.

 

I just had all these symptoms and it was the headgasket. Pull 3 plugs on that side and compare them, number 6 may be wet and will be spotless clean compared to others. If you can peek down into cylinder 6 with a flashlight piston top will be super clean the others will have carbon deposits. May be able to pressurize the radiator to about 10-15 psi with number 6 sparkplug removed and listen for air leak.
Here is where my gasket leaked into the cylinder, little hole next to exhaust valve. Even had little channels as water was flowing for a long time. After a long trip it sucked all the coolant out and overheated.
No water in oil on mine.


I hope it is not that

 

Gonna revive this.. haven't had a chance to pull the code yet but today when I started my truck, 06 V6, it flashes the light for a minute and then goes away. Hoping it is just a coil pack. As far as I know, my mfg date is after they started using the new part so head gaskets shouldn't be the issue.. but always want to think the worst lol

 

I'm curious how to find out what the mfg date is? I'm assuming it will be part of the vin?

 

I think it's on the door sticker. I found out that I'm an idiot though and my flashing light was just the "maint req" light flashing, which means I didn't reset the oil life internal counter when I changed the oil recently