engine light came on

[69_YENKO]

I have a 2000 SS A4,
i was cruising last night after a rain. after like 45min of driving the
"service engine soon" light came on. ive had the car a month now and this is the first time a light has come on. i figure maybe something got wet and tripped the light. the car didnt run rough and is running fine this morning but the light is still on.

i dont have a scanner or programer to use to pull the code is there a way to find out what codes have been set off without taking it somewhere?

[Dave M]

You need to scan it. There is no way of knowing the code without scanning it. AutoZone scans for free. Others probably do too. Scanners can be purchased for about $30-40 and would be a wise investment. Scan it and post the code, then we can start to troubleshoot.

[69_YENKO]

just got back from advance auto, they pulled codes:

PO172 system to rich (bank 1)
PO175 system to rich (bank 2)

what could have caused this? maybe the IAT of MAF sensors? car is bone stock never been messed with.
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[Dave M]

Fred or one of the others more knowledgeable could point you in the right direction. I could only guess. Either it's running rich, or it thinks it's running rich (bad o2 sensors?). Since both banks are doing it at the same time, I'd guess it's actually running rich. I would guess a number of things could be casuing this. How many miles are on the car?

[69_YENKO]

it has 33,152 miles on the clock

[94blackbullet]

that happened to me, check engine light, and it was the gas tank cap. it had loosened up and triggered the light. check that first before taking to a shop.

[hotwhip9]

those seem like the same codes that mine is shooting right now. I was told it is the O2 sensor on the drivers side, closest to the motor. I can get mine scanned again and post the codes, although i might just replace the o2 sensor and see if it goes away. Mine is running fine, just that light and the airbag light is on.

[69_YENKO]

after they scanned it, they deleted the code to turn the light off. it has yet to come back on after about 80miles. Im still unsure about why it was set off in the first place

[Dave M]

When the code is deleted, it resets all the sensors in the engine as well. It's as if you had the battery disconnected, the engine has to relearn everything again. It could take a few hundred miles (not usually) and several days for the puter to see signals from the sensors and relight the SES light.

I pulled the code from my computer to turn off the SES light before I went in to be inspected. You will fail emissions test if you have an SES light on, so I pulled the code. Well, I didn't know it reset everything else, and when I went to be inspected the computer read "not ready to be inspected." It knew I had reset everything and wasn't seeing data from all the sensors. A few trips later, the SES light always comes back on. So I just had to fight my laziness and fix the problem.