Check engine light goes off and on. Need to worry?

[joecan5785]

I own a 2007 Chevy Aveo with 65,000 miles. About two months ago, the check engine light came on, stayed on for a few days, then went off for about a week.Then came back on again for couple of days, then went off again for another week or two. Right now it is off.

Is there anything to be concerned about? About 2 years ago it came on and the throttle body had to be replaced. Six months ago, it came on but it was due to gas cap not securing properly. Both of these times the light stayed on.

Just looking for advice.

Thanks

 

[gwraigty]

Have it checked out. Some chain auto parts stores may do this for free. Otherwise, your auto shop will take care of it.

It can be frustrating. One time, the dealer couldn't get a code after the light had been on for a couple of days, then went off and stayed off for a long time. But most of the time, they've been able to find something and fix the issue.

 

[MRG]

Take to someone who has the equipment to get the codes. They tell you what components are complaining.

 

[Red Badger]

Otherwise, just give it time. It''ll let you know eventually.

 

[Spock]

automotive check engine lights are the equivalent of IAI aircraft... a single light on the dash that can mean anything from "your engine is on fire" to "a door is ajar".
Take it in to have the code read... from there you can figure out if its something serious or not.

 

[NW-Bound]

You can buy a device that plugs into the car OBD (Onboard Diagnostic) port, which then talks wirelessly to your smartphone via the Bluetooth or WiFi link to display a more detailed message.

Or places like Autozone or Checker Autopart may do it for you for free.

 

[jim584672]

Get an OBDII scanner. Lots of times it is a loose gas cap if it says it is an emissions control problem. The scanner should have a reset the codes option.

 

[ERD50]

You can buy a device that plugs into the car OBD (Onboard Diagnostic) port, which then talks wirelessly to your smartphone via the Bluetooth or WiFi link to display a more detailed message.

Or places like Autozone or Checker Autopart may do it for you for free.

+1 on that.

Here's the one I bought 5 years ago, just ~ $13 (cheaper and more flexible than any handheld scanner), and free phone/tablet app for access.

https://www.amazon.com/gp/product/B0051CAE1C/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The app will tell you the codes, with a history, and you can even reset them. NOTE - this won't allow you to pass a State Emission test - you need to complete a 'drive cycle' before they will show a 'ready' status. But at least the device will show you if they are 'ready', so you don't waste a trip to the test station.

-ERD50

 

[joecan5785]

Thanks for all who replied. I will look into it.

 

[imoldernu]

another inexpensive code reader w/ CD code explainer.
https://www.amazon.com/Coldcedar-EL...+code+reader&qid=1566592563&s=gateway&sr=8-15

And this video shows where the OBD2 Plug goes in.

 

[RetiredAndLovingIt]

On most cars just turn the key from the off to the run position 3 times back and forth and then the codes will display on the dash then you can google the code. Do not start the car.

Check this video

 

[RobbieB]

What is this "key" you speak of?

 

[RetiredAndLovingIt]

Ignition Key however it may not work for the Chevy, can't find any where that says that it will. Works great on PT Cruiser and I think all Chrysler models.

 

[gerntz]

Penny never worried about it & she did just fine.

 

[REWahoo]

A little piece of electrical tape will fix it.

 

[Car-Guy]

A little piece of electrical tape will fix it.

I actually did that once many years ago.... Got tired of looking at it...

 

[38Chevy454]

The likely reason the light is going on and then off and coming back is that you have some sensor that is starting to fail. The CEL is just the display the car's computer letting you know something is operating out of normal range. In your case it seems to be intermittent, but the offending part code will be stored in the car's computer and a scan tool will be able to read the code and help identify the problem. Just remember that a specific code may be caused by several factors, it is not always just one sensor. That is where a knowledgeable mechanic or someone with more advanced scanning tool can determine exactly what is going on that is causing it to set the code for out of operational range.

 

[RetiredAt55.5]

A little piece of electrical tape will fix it.

Some problems, like an engine misfire CEL, shouldn't be ignored. Or you can fry the catalytic converter by ignoring some CEL's.

That's the problem with the electric tape fix. It'll hide all the subsequent problems too.

If my car seems to be running ok, I like to clear the CEL with a scan tool, and see if the light comes on again.

 

[Bamaman]

A code just throws you into a direction of what to look for. Often you can just lookup the code number in the internet and it'll tell you the most often fix for that specific code.

Often it can be just a sensor that's about as easy as a spark plug to replace. Or, an ABS code can be a dirty wheel sensor that can be cleaned with Dawn. Throttle body problems are often just dust on the mass air flow sensor that can be sprayed with an aerosol cleaner.

And if it's a serious issue, you need to have a good independent mechanic shop that can address the problem. I avoid car dealership service departments like the plague--unless the factory's paying for the repair. My shop charges $40 per labor hour--less than half what dealerships are charging.

 

[jimnjana]

Toyota covered repairs on my 2012 Tacoma when check engine light came on. Known issue that was not under recall but they extended repair/replace warranty for certain fault codes. Repaired earlier this year.

 

[Jerry1]

The above advice is good, however, what I would do is recognize that you have a 12 year old car and if it is running well enough that you don’t sense a problem, then I would ignore it. The light is off. Who knows what it was. If it’s serious, it will come on again and start running poorly. Checking the codes could take you down a rabbit hole. The most I would do is maybe take it to a mechanic the next time I get an oil change and see if he’ll read the codes for free and discuss it with him.

Do you have a mechanic you trust? If not, I’d spend time on that while the light is off.

 

[FIREflower]

You can get the code read for free at pretty much any auto parts store. They also ten dot give free advice regarding the problem, which sometimes is spot on and sometimes not. But at least with the code in hand you know what possible things it might be and can plan from there.

 

[wolf]

Some problems, like an engine misfire CEL, shouldn't be ignored. Or you can fry the catalytic converter by ignoring some CEL's.

That's the problem with the electric tape fix. It'll hide all the subsequent problems too.

If my car seems to be running ok, I like to clear the CEL with a scan tool, and see if the light comes on again.

Correct. 02 sensor going bad, or somethine else, if ignored, can result in catalytic converter being ruined. Expensive to replace.

Also, I assume when OP, mentions engine light. It is "check engine", not a
"maintenance reminder" light.

 

[Koolau]

Car computer codes can be maddening. I had a car whose light came on. Had it checked out. It basically said it was the fuel system. The garage asked if the car had any symptoms. Since the answer was "no", they suggested ignoring it. They DID offer to run it down, but they printed out about 20 things it COULD be and the total cost to check each one would add to a few hundred dollars unless they got lucky and found it quickly. I let the light stay on for several years until the tranny gave out (a separate code, heh, heh.)

The code items were as simple as the gas cap being loose to the vapor recovery system needing to be replaced. Never had a symptom I could identify.

YMMV

 

[ERD50]

Car computer codes can be maddening.

... they printed out about 20 things it COULD be and the total cost to check each one would add to a few hundred dollars unless they got lucky and found it quickly.

... Never had a symptom I could identify.

YMMV

How is that different from not having the codes?

If I have a symptom, there can be many causes, sometimes hard to isolate. If you sense some misfires, could be anything in the ignition system, (plugs, wires, coil - or points, condensor, dwell, timing, or timing advance in the old days), fuel system ( fuel pump, any hose, fuel injector, air filter - or about a zillion things in the old carburators in the old days), a vacuum leak, a bad valve(s)?

The codes often are very specific. I had a code on my Volvo - engine not coming to temperature fast enough. I had a temperature gauge on the dash, and was accustomed to watching it (as a guide to turning on the heat in winter), and I could sense no difference. But the computer is sensitive enough to detect this.

The most common issues were a bad sensor and a bad thermostat. Both are easy to replace, the thermostat was cheaper, and I could get one that day at a local auto store. That fixed it.

If you are going to say "Why fix something if you can't detect any problem with the performance of the car?", there is a simple answer - "The Environment".

All these pollution controls on cars do a fantastic job of reducing emissions, IIRC, some pollutants are reduced by thousands of times over the cars in the 60's. For that level of operation, everything has to be "just so". Any little offset can throw the emissions way off. And as some have said, an otherwise undetected problem may ruin your Catalytic Converter, costing $$$ and creating more pollution.


I'll take the codes. They are great, but like any diagnostic tool, they aren't magic. A volt meter or an oscilloscope doesn't tell me what the problem is either. I've never had a 'scope tell me "Replace Q302 and C104". But they are valuable for finding the problems. Codes are just a tool, not magic.

-ERD50