Newbie with typical P0171 issue

[wayneboard2]

Ok guys so here is my delimma. I did go thru and search for this problem and I did find some threads about it, but I kinda left more confused than when I started. Her is my story.

3 years ago I put a K and N in my 2000 toyota 4 runner, 3.4 ltr V6 SR5. it had 50K on it. I noticed I had some CEL come on, turned out to be a dirty MAFS. Cleaned it, took care of the issue. Well recently it has started coming on again. I did a read from auto zones scanner and it gave me the 171 code. Well, I cleaned it again with proper cleaner, and it still comes back on. I checked the gas cap seal and it's in great shape. I always click it 3 times, never overfill, etc, etc. I am in the process now of doing a lot of tune ups such as new plugs, draining coolant, etc. It had been off for 2 weeks and when I changed my sparkplugs it came back on again and attempting to clear it just works for a minute or two and it comes back on.. Now this is a CA "model", but the sparkplug replacement went just fine and it runs great now. Do I need to disconnect the battery to resolve this issue to see if the cleaning worked or does the clearing of the code with the scanner do that?

SO, my thinking is that it is "obviously" either one of the O2 sensors or the MAFS. My question I guess is, how do I find out exactly what one it is since the cleaning fo the sensor didn't work? I can replace any of these parts themselves, but it's finding out what part is the right one to fix thats the delimma. I live kinda out in the boonies and my closest mechanic wants $66 to scan it to tell me the problem. Will he be able to tell me what part is wrong or will he just make me pay him to end up in the same predicament as I am in now?

Sorry for my first post being a novel but I wanted to paint as clear a pic as possible. Thanks for any help anyone can provide.

 

[greasefingers]

Massive intake manifold leaks, dirty or failed MAF, or the O2 sensor is the issue.

There is a heating element inside the MAF (just like the O2 sensor) You could check for continuity for these two wires, if you know what wires to check for. Neither sensor will function properly if the heating elements do not work.

 

[ebelen1]

Had the same issue w/ my '99 and decided to do the front 02 sensor (really called an A/F sensor). Did this as I hit 100k miles and knew this was an item that normally went.

After doing this, the code still would not go away for more than a few hours. Cleaned the MAF to no avail. Decided to buy a new MAF and ever since, no code.

To answer your question, there's no real way to know what the issue is but rather do the cheapest or more common replacements first and hope to nail it. Either way, the A/F sensor will go bad so I'd still start there.