CEL Code#171

[Raven]

My check engine light came on Monday afternoon. I read the code when I got home. It was #171-System too Lean (Bank 1). I brought it to the dealer yesterday for this and a couple of other warranty issues (replace 2 peeling hubcaps, replace rear pass. speaker). They told me it is caused by my CAI and Magnaflow exhaust. They said not to worry about it, just read the code and reset it once in a while. I find this strange because both the CAI and Magnaflow have been on the car since it was new last fall and this is the first CEL. I'm going to try disconnecting the battery for a while and see if maybe the computer will relearn and not trip the CEL. It could be due to the awesome weather we have been having 12 C (54F) and sunny, the gas pedal has been spending a lot of time pressed firmly to the floor which didn't happen much all winter with the ice and snow. Any thoughts on the matter would be appreciated.

[4azdmunky]

what was the voltage on your O2 sensor?I am waiting for a replacement O2 sensor that went tits up and threw a similar error. To be honest, I would pick up a OBDII scanner that is compatible with the ISO standard our car uses and read it yourself. Just pulling the code is nice, but to be able to read the sensor statistics is worth the $100-$130 (scantool.net) it will pay for itself the first time you use it. Pulling the code is 1/2 the battle, watch the sensor statistics for about 3 minutes usually tells you what is wrong.It has been my experiance that dealerships are too much in a hurry to take the time to do a full complete diagnostics. My car is still under warrenty, and I still do all the work myself (unless dengine/tranny internal related) because I cant trust dealerships anymore. The sad thing is the dealerships in Aurora CO are actually not that bad, but I just dont have the time to waste by going back again and again for the same problems.In fact I trust the support on this forum 100% more than the support from a dealership. The people here have practical knowledge.

[4azdmunky]

BTW Bank1 is related to your first O2 sensor. It is not because of your CAI or your exhaust.

[goodvibe]

You could try cleaning the MAF. If it's dirty, you can run leaner than even the adds cause. CAIs run lean except at full throttle at HP peak where you're normally quite rich. They make much of their power by getting the A/F optimised at that point. It results in other RPMs running lean but ussually not enough for a CEL on a base.

[joatmon]

My pubs say P0171 means:When the air-fuel ratio feedback is stable after engine warmingup, the fuel trim is considerably in error on the RICH side(2 trip detection logic) and can be caused by Air induction systemPCV hoseInjector blockageMass air flow meterEngine coolant temp. sensorFuel pressureGas leakage on exhaust systemOpen or short in oxygen sensor circuitOxygen sensorECM

[Raven]

Thanks joatmon.

[goodvibe]

http://newcelica.org/forums/showthread.php?t=46353 Lean, Check this link and clean your MAF.

[Raven]

I'll try that. I don't want to screw up the MAF though, it's expensive.

[joatmon]

yep, my 2003 pub says Rich, the 2004 pub says lean. Must be an error in the 2003 version. sorry 'bout that, hate it when I mislead, at least I meant well

[Raven]

I cleaned my MAF with carb cleaner and presto, no more CEL. Thanks guys for the help.

[goodvibe]

Glad to hear it worked. I'd only clean the filter every 30km or more and easy with the oil. AEMs new dry filter does a better job of keeping out dirt and no gumming up the works.

[Raven]

It's funny that it ran fine for a couple of months. Mind you the fouling of the MAF did coincide with much, much warmer weather which would thin the filter oil and allow it to be sucked upstream into the MAF. No fouling was visible but it does not take much, they are very sensitive.

[4azdmunky]

You were right. After cleaning my MAF sensor the problem went away.Now, i get to try and return a O2 sensor that was bought that was the wrong part.grrrr.....

[dave9382]

i have been having this persistently since I put in my short ram but I believe we massively overoiled the filter and some of it got sucked into the pipe. Should cleaning the MAF be a good suggestion if it keeps happening and how should I clean it?? with what solution and implement (like a q-tip?) Ive looked at it and it didnt look dirty or oily at all but I guess looks can be deceiveing..

[joatmon]

Quote, originally posted by dave9382 » Should cleaning the MAF be a good suggestion if it keeps happening and how should I clean it?? with what solution and implement (like a q-tip?) seems like a quick easy thing to try.I thknk the procedure is pretty muchdisconnect the batteryremove the MAFhose off the MAF with brake cleanerput the MAF back in connect the batteryI wouldn't actually touch it with a Q-tip or similar thing, just spray it clean

[Raven]

I sprayed mine with carb cleaner, it's milder. Don't touch the little wire with anything, just spray it clean. Wipe the inside of the short ram intake with a clean lint free rag.

[dave9382]

by carb cleaner you mean carburator I assume? Do you have an example brand or something I can get at auto zone and does it come in a spray bottle already? So I guess I would just spray and let dry??

[joatmon]

I used brake cleaner, since it evaproates completely, where carb cleaner tends to leave some residue.

[Raven]

Kleen-Flo Carb and Choke Kleen is what I used, spray can. Just spray a little on and let it evaporate for a while.

[4azdmunky]

same here, had severl problems with over oiling my K&N. I have used bith Stereo Cleaner (Radio shack, also called electronics cleaner) and carb cleaner. Both worked fine with no ill effects (so far).