Comments on: P0171 Check Engine Code on 2000 Toyota Corolla

By: Mark

Mark — Tue, 03 Jan 2012 19:30:48 +0000

At first it was a spark plug, the second form the driver side number 3 to be more precise. After removing it I noticed it was wet due to it misfiring. That spark plug was installed corretcly, so how could it get wet inside? I’d understand if it was lose allowing moisture to get in it, but it was not lose. So, after replacing all 4 spark plugs I still get the same problem in the same spot, which is, number 3. It isn’t the spark plug now, it’s the cylinder itself that is misfiring now. Can it affect my Massive Air Flow (MAF), OS (oxygen sensor), and cause low fuel pressure?

By: Tim

Tim — Sun, 26 Jul 2009 19:17:13 +0000

First I changed the oxygen sensor and that wasn’t the problem. Then I used electronic cleaner to clean my MAF sensor. The sensor has a port with 2 little diodes, you must clean those. You may need a flashlight to see them. My car has been fixed for about a week now. While doing this, disconect the battery cable, to reset the computer. This worked for me, so good luck.

By: Tim

Tim — Wed, 22 Jul 2009 00:27:42 +0000

I am having the same problem with my 2000 corolla. I replaced the oxygen sensor in the exhaust manifold and it didnt help. I also cleaned the MAF sensor and that didnt help. I am not sure what the problem is.

By: DrStorch

DrStorch — Mon, 07 Jan 2008 16:38:36 +0000

The problem might stem from a faulty gas cap. I was getting a light after the tank was down to about 1/4 and re-set after fill-up. Replacing the gas cap eliminated the problem. It seems that the vacuum spring in the caps goes bad after a while. It might be worth a try.

By: Jason Bartel

Jason Bartel — Mon, 10 Dec 2007 12:45:17 +0000

I am having the same problem with a carolla that I have been working on. One other thing I was told to check is if any of the cylinders are misfiring. Not sure how much good that might do.

By: Antonio B

Antonio B — Thu, 05 Jul 2007 22:05:36 +0000

I had ther same code for my toyota corolla 2001 I clean the MfS the problem disappear for weeks but after A long trip the code comes back. I think i have to change the oxinge sensor. I wish you luck>

By: ejohnson

ejohnson — Wed, 11 Apr 2007 16:05:13 +0000

My check engine light actually turned off after hitting a big bump in the road. This is the first time the light turned off w/o me having to clear it using a reader. I’m pretty sure it will turn back on though, it’s still not performing well in certain parts of the power curve.