General Maintenance & Repairs - service engine soon?

Last Thursday night i went to get gas at chevron and i forgot to close the gas cap all the way like your suppose to as i drove off the service engine soon light came on but it was cause i didn't close the cap all they way in after i tighten it i drove to work the light turned off i drove it Friday Saturday and on Sunday is when the light turned back on but why? What could it be i need some advice? I just came back from Oriellys and they scanned it said code definition: fuel trim system lean bank 2


357810 could it be cause of my gas cap cause ever since this situation happened the service engine soon light came on?? Thanks ls1tech

Just have the codes cleared out, they should be able to do this for you, or just spend the 40$ for the basic hand held. I got tired of going back and forth trying to diag a SES light. Unhooking the battery for an extended period also helps the PCM re set and basically start to relearn. Over time the PCM will refine and re adjust due to what it's reading while you drive.

Maybe its so refined that minor diff in readings due to the loose gas cap will throw the car into a tizzy but clearing out the code and resetting the PCM will fix it.

Don't worry about it, but when you can afford $40 or $50 bucks get yourself a hand held code reader. Then the next time this happens you can read the code and clear it yourself.

I bought mine for about $50 and have used it to diagnose quite a number of issues with my car and other people's. An OBD II code reader will work on any car and is one of the best tools to have.

My first Firebird was a bitch about setting the light for a loose gas cap. And being in Oregon I can't pump my own gas, so there was always some idiot pump jocky causing the light to set on.

Thank you guys for helping me out I'm always opened to learn new things, so either though It's running lean the hand held code reader will still clear it? I thought that i was going to have to buy a new gas cap and get a fuel injector cleaner to pour on the gas tank before i pump gas and that would have taken care of my problem?

Usually fuel trim lean is an O2 sensor. Bank 2 would be the pass side. Leaving the gas cap off will usually set off an evap code. Just unhook your battery for a little while then hook it back up and see if the code comes back. If it's been a while since you replaced the O2 sensors you may want to consider replacing them. If you had access to a scanner that shows live data you can see what your O2 voltages are. If you replace them get AC Delco O2's!

Usually fuel trim lean is an O2 sensor. Bank 2 would be the pass side. Leaving the gas cap off will usually set off an evap code. Just unhook your battery for a little while then hook it back up and see if the code comes back. If it's been a while since you replaced the O2 sensors you may want to consider replacing them. If you had access to a scanner that shows live data you can see what your O2 voltages are. If you replace them get AC Delco O2's!

Okay thanks i will consider that, the trouble code: P0174 and the code definition: fuel trim system lean bank 2, they told me my car was running lean I'm just trying to fix it i don't like ses lights. They gave me a paper of possible causes and reported fixes but i don't know what it could be?

Here's a link with some good info on the code and other causes/things to check.

http://ls1tech.com/forums/generation-iii-external-engine/737349-help-code-p0174.html

Thanks in advance i got a lot of information now to fix my problem I'm going to clean my MAF sensor right now with rubbing alcohol and wet a quetip hopefully that will take care of it and reset the code

Yea, get new 02 sensors if you need them at rockauto.com.....NOT the dealership. There are no such thing as AC Delco 02 sensors anymore, they stopped making them like 5 years ago....GM re-boxes $35-$40 Denso 02 sensors into their GM AC Delco boxes and then they charge you upwards of $180 each at the dealership. So just buy Densos at rockauto.com or amazon.com

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Thanks in advance i got a lot of information now to fix my problem I'm going to clean my MAF sensor right now with rubbing alcohol and wet a quetip hopefully that will take care of it and reset the code

I wouldn't touch the MAF sensor tiny wires with a q-tip....they can break, then you'll be buying a new MAF.

Buy a $7.00 can pf MAF Cleaner and spray the hell out of it through the screen. Spray everything.......

Hit your IAT sensor with a shot too........then the rest to clean the inside of the TB.

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^^^^^^^^^^^^^^^^^^ this!

So my gas cap is alright then or what? Click on my pic of the gas cap and check it out let me know what you think should i buy a new one?

So my gas cap is alright then or what? Click on my pic of the gas cap and check it out let me know what you think should i buy a new one?

The gasket on the cap looks like its cracked a bit.......but can;'t really tell how bad. I tossed my factory original gas cap last year, it was 14 years old. It was fine.

I bought a nice Stant locking gas cap for like $10.00 at PepBoys. They cost $12.00 at rockauto.com.

Get one......

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I'm slacking it i was going to buy one yesterday but the guy at oriellys told me mine was fine but it's 13 years old so i'm going to buy one tomorrow but how do you install them cause they have a cord attached to the cap from the gas tank?

thanks for the help