Intermittent "service engine soon" light..

[sleber]

My wife's 02 suburban (38K miles) is getting an intermittent "service engine soon" light and I was wondering if there is a way I can pull the code(s) or if I need to take it to Autozone for them to do it(if they can). The only problem she has noticed is the cold start knocking. Once I get the code where do I go to find out what it means?

Thanks

[biggbabysweetz1]

if you dont have a scanner your best bet is to run to carquest, autozone, advance auto... etc. most places can scan your vehicle for free while others cannot but have the tools for you to do so.
most obd 2 scanners will give you the code and a brief description such as p0402 "Cylinder 4 misfire detected" <this is an example and is not the correct code for a missfire<

im betting on an o2 sensor going out.
also you can post your result on automotive forums and we will do our best to decipher it!

[16th hippy]

p0402 "Cylinder 4 misfire detected

P0304 misfire detected cylinder 4

[Blue Bowtie]

Once you get the erro code number(s) you can find the information for each code at many places on the www.

[sleber]

Thanks guys. Would it be normal for an O2 sensor to go out at 38K? If it turns out to be the O2 sensor is it pretty easy to change?

[16th hippy]

not hard at all if you just use some kinda penetrating lube...i like PB Blaster myself....wd40 works ok too. get a 7/8" or 22mm wrench, or even a medium size crescent wrench will do. go from the bottom. i have had a couple vehilces with less than 10K on them and 02 sensors go out....seen a few with 200K and factory o2 just finally went out.

[biggbabysweetz1]

Originally Posted by sleber

Thanks guys. Would it be normal for an O2 sensor to go out at 38K? If it turns out to be the O2 sensor is it pretty easy to change?

as stated above they can go out as early as 10k miles, it depends on a lot of variables temperature, use, abuse.... that kinda thing. my 89 burb went 350,000 miles on the original O2 sensor, and when i replaced it (never threw a light just figured it was time) i didnt see much improvement in fuel mileage and power because the original was still functioning properly.

with your vehicle... if it turns out the o2 sensor is malfunctioning, a replacement costs around the 70 dollar range. you may acctualy have 2 or more in your vehicle, i personaly would go with the oe style (universal is around 60 bucks) cause all you have to do is unplug the old one from the harness and plug the new one in.. universals you need to splice

most auto parts stores also have an acctual O2 sensor socket for around 10 bucks but as stated before the 7/8 sae or 22mm metric wrenches will do fine.
just dont forget the penetrant otherwise your gonna have a push and shove match with the o2 sensor, and about 80% of the time they win

hope this helps!
Good Luck!

[sleber]

My wife stopped at Autozone on the way home from church but the light was no longer on and the guy said he could not pull the code(s) unless the light is on. I thought the system retained the codes until cleared but if the light does have to be on I guess I'll have to wait until it is on all the time to get the code(s).

[16th hippy]

autozone uses a cheapy scanner, and may not e able to read codes if not current(setting the light).

[777stickman]

I thought the system retained the codes until cleared

The computer stores codes in "history". If a problem gets fixed and the "history" codes are not cleared using a scanner the comp will clear them after a determined length of time without that problem coming back.

So, here's the ? to ask next time you take it to someone. Will your scanner read history codes??? You may have to pay $20-40 to get that done. Make sure you get all the codes. When you do post back and we'll try to help...........Steve