If you erase the "Check Engine" light will it come back on?

Yesterday we were doing a "Tune Up" for my truck which consisted of oil change and filter, spark plugs, and engine filter.

-Plugs are OEM
-Filter is FRAM Ultra Synthetic (ran it in previous oil changes)
-Engine Oil: Royal Purple 5w30 (ran it in previous oil changes)
-"Upgraded" K&N Filter


Finishes everything up and the "Check Engine" light comes on. We checked everything by "looking" to make sure no hoses or such were disconnected. That didn't turn it off.

We thought it may have been the "K&N Filter" maybe the engine is not use to how thin it is in comparison to the OEM filter, so we switched it out and in the process we noticed a Spark Plug connector was disconnected, most likely happen when putting the intake back together.
Although that didn't turn it off either.

Kinda got us thinking what could be the problem. So we removed each spark plug and made sure they were gaped to "0.44" and put them back on.
And again that didnt turn it off.


The engine seems to be running great and no awkward noises. So we used the Ultra Gauge to ignore the "Check Engine" light hoping the light will turn back on if indeed there was a problem "we had read, its suppose to come back on if there is a problem".

The light has been ignored(turned off) and has not come back on yet. I've driven the truck about 30 miles since this happen and kinda has me thinking now, will the light actually turn back on if it was ignored????





Thanks ahead of time

 

Could have been gas cap not tightened enough? Otherwise you are correct if there is a problem the light will come back on. If the light stays off its really hard to say what triggered it. I hope it stays off for ya

 

I would clear it and see if it comes back. I had an error come up on my Ranger and when I cleared it it never came back

 

Wy didn't you check the code when you cleared it to see why it was throwing it

 

AFAIK once the check engine light illuminates, you need to clear it from the OBD port. If it stays off then you're good to go (hopefully), if it comes back on after it's been cleared then the problem persists.

 

If there's an issue, it'll come back on. I had one pop up on a Jetta I had, had it scanned and it was nothing. Cleared and didn't come back.

 

If you had a poor connection on one of the plugs, you would definately get a "check engine" light. You reconnected it and cleared the codes. Now the engine is not recording a miss fire on the bad plug wire/cylinder. You are good to go. The light won't come back if nothing is amiss.

I'm curious how you got the engine ECU to "ignore" the CEL? If you just disconnected the battery for a few minutes, that would work just fine.

If you are going to continue working on youor own vehicle, a decent, cheap scanner will be a great purchase. I got to warn you, once you start learning how these tools work, you will want to continue to learn more and more about how our truck engines operate. It's kind of an addiction...at least for me it is.

KO

Edit:

I didn't see that you have an Ultra gauge. That is a decent place to start. If you found a bad connection on one the wires, you could have "cleared" the code instead of "ignore". If you run with the UG connected all the time, you want the UG to record the code, ot ignore it.

 

The gas in the vehicle could be of a low quality I know that has happened to me before.

 

Mostly correct, The truck CEL light will still come on but the UG has been told to ignore the issue. The truck can't tell you what code has been triggered, the UG can tell you the code number and then you can go to the internet and punch in that code number to learn all about what causes it.

 

if it comes back on, read codes with your OBD reader and look them up or post on the forum, peeps around here have dealt with about every code ever thrown and can help you out real quick

 

you learned any tricks in your exploration of software you can share? on one of my other vehicles i learned all kinds of lil' extra features that could be turned on with a programmer.

 

was it a PENDING code?

I know u can turn IGNORE PENDING codes with ultragauge

 

I'm pretty sure, he didn't note that if he was here asking questions. Thats fine, how are you going to learn without asking questions.

KO

 

I don't have a lot of time right now, been awake since 3am, so getting ready to call it a noght.

One of the best things that I can point a person who has interest is to go to Amazon and buy the TechStream softaware and cable. I think its around 35 buck now. This is the exact software that the dealers use. All I can say is OMG. The info and changes you can make to a Toyota vehicle is is awesome! You won't be able to change any engine parameters, but you will get access to all sorts of options that only the dealers can do. Example, turn the alarm on or off, adjust the key chime, turn off the seatbelt chime, make the windows roll down with the key (limited or up package), compression checks, light checks, gauge checks, fuel gauge calibrations, tranny temps. I'm going by memory here, been a while since I played with mine.

You will need an old laptop that runs windows XP with a 32 bit OS, but there is a work around that allows you to run the software on a 64 bit operating system.

I ahve to warn you, it took a while for me to get my TS program to function properly, it was quite clunky, but I attribute that to me not being very computer saavy.

Later

KO

 

Yes, if there is an issue. I did a spark plug change, got a hesitation and bog from engine. Very randomly, I didn’t know what it was. Until 5-7k miles after it started doing more frequently and got very bad. I finally got a Check Engine Light, scanned with hand held scanner, and found a misfire on cylinder 4. Erased it and came back again after driving. I ended up buying a new Coil, still didn’t fix problem. I ended up pulling spark plug and replacing it. Fixed the issue right away. Faulty spark plug was gapped okay, nothing visually bad about it. I only buy Toyota OEM parts from dealer. I do got to say, it took awhile for check engine light to come on initially, even slight hesitation didn’t throw check engine light. It took some consistent misfire, crappy acceleration, it drove me nuts.

Forgot to mention. I used a friends handheld reader, Actron I believe. I erased after I read it and came back on after driving again with misfire.

 

What code was present?

 

thanks bro! i will try to get one! as far as laptop setup, i have a few ready to use that i used on other vehicles and to program eeproms and atmels. gotta always keep a laptop or 2 around with xp and serial ports and even with 98 and serial ports

 

I can't remember, scanner gave code and description.

 

Thanks all of you for the feedback!
The light has not come on, I would assume it had to come on already since I put 100 miles on it as of now, I was driving a lot yesterday and no weird noise, no smell, no signs of anything being wrong.

My only concern was; What if there was actually something wrong and the light just wouldn't come on anymore because it was turned off. That's what has me thinking a bit, another thing is why wouldn't the light turn off by itself if I had fix the problem?

I didn't drive it with the check engine light on so my other assumption was it was probably going to turn off by itself after I had driven around a couple miles????

 

Doesn't turn itself off. Has to be reset to turn off once it's come on.