How to clear "Check Engine Soon" light

[amain]

I have a 2000 Silverado with a 4.8L. It is real cold here in the cornpatch this week and today when I started my truck, the engine sounded rough at first and then the "Service Engine Soon" light came on. After I revved the engine a bit, the engine seemed to smooth out and everything was OK, but the light is still on. As I suspect that it all had something to do with a glitch caused by the cold weather, I would like to just clear the light and see if it stays off. I figure if there actually is a problem, a new code would be generated and the light will come back on.

So how do I clear the light? Does disconnecting the battery do it, or is there a memory chip in there that will keep the light on when I reconnect the battery?

Thanks for any input here.

[buttnekked]

it will probably stay on; most codes are stored in the computer. Your local chain parts store (autozone etc...) should be able to help. Many of them can pull the codes and clear the light.

[busta]

disconnect the battery wait at least 5min better if left longer and then re-connect this will clear codes if you have aproblem the code will show up again

[amain]

Thanks, guys!!! I'll give it a try and see what happens.

[kenny-1907]

From 99 and up , 2000 for sure disconnecting the battery does not clear the codes. All disconnecting the battery does now is reset the computer, does nothing to the codes.

[GMMerlin]

I got a novel idea..instead of ignoring the problem and masking it by trying to turn off the light...why don't you have the code pulled and see what was going on and fix the problem?

[amain]

Mostly because I don't think there IS a problem. Light came on during startup with engine exceptionally cold and engine ran rough for about 10 seconds and then everything was fine. Thought it would be easy to just reset it and it would probably not re-occur. Didn't know it was a big song and dance to just shut it off. I'll go to Autozone and have it cleared. Don't figure anyone at Autozone will be able to accurately diagnose anything from an ambiguous code and I don't intend to let a dealer mechanic lay his hands on it as long as weather conditions are abnormal. Older Chevies used to be reset by shorting a couple of contacts on the harness connector, but now everyone seems to think it takes a $300 code reader. So much for progress through technology.

Thanks for the input, I'll post the results next week as I will be off work and will have some time to screw with it. Temps should be much warmer, too.

[dcarson]

We had a bit of sleet and ice where I was Sunday night, and Monday morning my service engine light came on too. It was one for about five minutes and then went off. Have no idea what happened.

[GMMerlin]

To test a componants integrity, sometimes it has to be put to the extreme (hot or cold) before a failure will show up.
This could be an indication of a future failure..thats way I suggested you have it checked..next time it might happen 2000 miles away from home and leave you in tennis shoe mode.

[amain]

Well whaddayaknow, the SES light went out all by itself! Just like it did for dcarson above and for my son last week with his 2002 Silverado. I suspect the diagnostic module detects a low voltage condition which sometimes occurs while starting a cold engine and after a certain number of subsequent startups, a non-recurring condition will cause an automatic reset. Certainly doesn't warrant an expensive trip to the dealer or, in this case at least, even a trip to Autozone in butt-freezing cold weather.

Too bad GM didn't design the system to simply display a code, or better yet a brief description of the problem, on the dash display that is already provided, but then GM and its Master Technicians would have to find another way to put their kids through college.

[dcarson]

Actually, according to the manual, the SES light monitors exhaust and emissions information. Extreme cold conditions create much denser air which may have affected the mixture and therefore the exhaust.

But in all honesty, all I know is what I read. I dont know enough about these new engines to speak with any authority.

[srvfan]

Mine came on this week... Very cold here in Ok.... I had fillled tank with premium gas.. Took to autozone to read memory... It said "engine to lean"... Im assuming it meant the fuel.. any way he reset it.. Ok now.. never did run any different... I bought this vehicle used so I dont really know the maintenance history.. It has 98K think ill go ahead and change the fuel filter.. and tranny flush probably..

[dcarson]

that makes sense. I do not know a lot about truck engines, but I do know about aircraft engines. The cold air is more dense, so with the same fuel spray from the injectors, the percentage of the fuel is less, and it shows a lean mixture to the computer.

[GMMerlin]

the fuel mixture is calculated by air and coolant temperature and is adjusted for temperature.
The PCM adjusts the injector on and off time to maintain the 14.7 to 1 air fuel mixture at all times.
My point was to at least find out what the code was..It might be nothing or it could be the indication of a problem further down the road.
The PCM has not reset, but the self diagnostic test has passed enough times for the PCM to determine that the fault is no longer present at this time.
The code is now stored has a history code.
As far as putting my kid through college...helping people here on AF hasn't put a penny in my pocket.

[dcarson]

Like I said before, this is my first ever 4x4 and I am learning. This is also the first GM truck I have ever had. I was having new tires put on my truck Wednesday, and asked if I could go check out the brakes while they had the wheels off. The brakes looked good, but when I checked the play on the steering linkage, I had a lot of play when rocking the tires front to back. Not much from top to bottom. On the 4x4's with this independent suspension stuff, does that indicate excess wear in the steering? this is a 99 (new style) 2500

Would this be the reason why the last set of tires had really weird wear patterns on the front. There was aabsolutely nothing consistent with the tire wear on either tire. one section would be cupped, the center tread was more worn than the next two sections and the outside sections were well worn also. Flat spots and bulges showed on the center tread strip only with nothing on any other tread areas like that.

When I pulled them off I also noticed for the first time that they were 4 ply and not LT tires