Check Engine Light - on Sporadically

[NumberCruncher]

So my check engine light on my 2000 Toyota Camry has been on and off three times now in the past couple of weeks. It'll be on for a day or so, then off the next few days.

The last time it was on was Saturday, and I made sure to tighten the gas cap, as I read this was one of the most common issues.

Should I be worried? What other things should I check? Should I take it in to a mechanic to get the codes read? It has had an oil change recently.

[zataks]

Often, places like Kragen, Schucks, O'Reilly, Napa, etc auto parts stores will read your codes for free.  Many shops will too. 

Check engine lights (CEL) are kind of a 'dummy light' though and kind of a general warning; it could be any number of things.  If it's your only means of transport, get it checked out!

[Exflyboy]

If the CEL is eventually turning itself off, it means there is a code that is getting set but it is not "Latching". A number of things will do this.. The occasional misfire for example.

Like the poster above suggested.. next time the CEL is on go down to Autozone or similar and have the codes read.. That will at least give you a place to start looking.

Frank

[Greg]

I'll also recommend checking for any stored codes.  Some codes store, some things that trigger the light don't cause a code to be stored.  But check, then you'll know that whatever is causing it is too intermittent to worry about yet, for the most part.

If you can get to a code reader before it goes out you may be able to see what the problem is and fix it before it becomes worse and affects other things.  Keep in mind it's helpful not 100% accurate.

For instance a friend brought their truck to me with the engine light on.  Checking the codes showed a certain intake air temp sensor as bad.  Turns out one of the wires to it was broken.  So it's helpful but you still have to use your head when making repairs.

[El Marinero]

Ina similar situation, I bought myself an OBDII scanner.

They are cheap (some less than $20) and easy to use. You don't even need to look under the hood, and it takes only a few minutes to get a readng

Once you see what the code is, you know more. Then you can make the decision whether to go in to the shop.

[hybrid]

I'd bet good money that you have an O2 sensor going bad on you. No, it's not the end of the world, and I would get it checked out at one of those part stores that offers to check for free. Then find a shade tree mechanic looking for a side gig who will install it for $100 or so.

[Ohio Teacher]

I guarantee that when you get it checked it will be P0420.  We have had 3 Camrys all do the same thing.  It is the generic Emissions code that can mean anything from the gas cap to the O2 sensor(s) to the catalytic converter(s).

I run my 2003 Camry with the light on and now know it to definitely be the rear catalytic converter as I can hear it breaking apart inside as I drive it.  But, an 11 year old car isn't worth spending $1000 on for a fix that isn't absolutely necessary.  It's just an emissions thing, and as long as I continue to get 35mpg, I will take solace in the fact that the additional particulates that I am spewing into the atmosphere are balanced out by the fact that I am burning less gas. 

[theSchmett]

Until you need to get your emissions inspection done...

Have a "bigbox auto" pull the code for free and definitely do what was said earlier, pull stored codes.

[HairyUpperLip]

most auto parts store will scan for free

have them scanned and write down the issues

post them up and I'll help you research what it could be

thanks

[Zamboni]

I feel you pain . . .

My 2002 Prius has had a sporadic check engine light for 3 years now:  always the catalytic converter code.  The last time the CEL went out it had been on continuously for a couple of months so I thought maybe the bulb finally burnt out, but then it came on again a few days later.  Now it is off again.  Sigh. 

Somehow I have lucked out and it has been off long enough to get it by the inspection each year, and it still passes emissions with flying colors and gets 44-45 mpg.  I'd just bite the bullet and spend the $800-$1000 on the repair if it weren't for the detail that I only paid $3000 for the car.  I did rejoin AAA this year, just in case; it has already paid for itself.

Yes, I do get "Penny, your check engine light is on, shouldn't you check the engine?" jokes from my friends (all nerds, the company I keep.)
https://www.youtube.com/watch?v=1W5PCYFXLJ4

[Ohio Teacher]

Until you need to get your emissions inspection done...

Have a "bigbox auto" pull the code for free and definitely do what was said earlier, pull stored codes.

Not sure if you were responding to me but, just in case, Ohio doesn't have emissions inspections.

[Kriegsspiel]

Random car warning lights respond to strong disciplinary action. I've corrected many of them* simply by punching or slapping the offending area. This usually will do the trick.

*also works on tactical radios.

[schimt]

also a note, generally the check engine light will flash to signify a serious issue that is occurring at the moment, and hold solid for something that is not so pressing or not currently taking place. As others have said, go to autozone and have them scan the car for codes. Then let us know what the code was for or just google the code along with your car model and year and you should get plenty of information on most probable causes.

Good luck

[theSchmett]

@Ohio Teacher - just in general, in case anyone had forgotten, the Check Engine Light is an auto fail on emissions inspections.