Check Engine Light Code P0171

[Rumundo]

My wife has a 2000 Protege LX with the 1.6. The stupid check engine light is on. I took it to Auto Zone, and they diagnosed code P0171, engine running too lean. SO....I poured a bottle of fuel injector cleaner into the tank and ran it hard with the Overdrive off so it could really get in there. Then I reset the computer, and 2 days later, it came back on. My wife has driven it for a couple of days now, and the light is back on. I reset the computer again, and drove it around myself. Within 20 minutes it was back on. I don't want to take it to a dealer if its something I can fix myself. I think the power is there, but then again, i am used to a V8, and the power is NOT there...lol. Any ideas, thoughts? Thanks.:( :wtf:

[blynzoo]

Originally posted by Rumundo
My wife has a 2000 Protege LX with the 1.6. The stupid check engine light is on. I took it to Auto Zone, and they diagnosed code P0171, engine running too lean. SO....I poured a bottle of fuel injector cleaner into the tank and ran it hard with the Overdrive off so it could really get in there. Then I reset the computer, and 2 days later, it came back on. My wife has driven it for a couple of days now, and the light is back on. I reset the computer again, and drove it around myself. Within 20 minutes it was back on. I don't want to take it to a dealer if its something I can fix myself. I think the power is there, but then again, i am used to a V8, and the power is NOT there...lol. Any ideas, thoughts? Thanks.:( :wtf: check your fuel delivery system. Fuel pump and injectors. If you wish, you may replace the injectors yourself. Often, visual inspection of injectors can reveal the problem. However, the fact that you used injector cleaner, and the problem came back a couple days later. This (hopefully) might mean it's not a prob w/ your car. Try filling up from empty at a different station with higher octane gas.

If it IS your car, it's gonna be your ECU, pump, or injectors. the OBD "lean" code is a real general one, but I'm not sure if it's generated by the O2 snesor or by monitoring timing. Knowing that could help a lot.

This may be something for a shop, unfortunately, unless you have the scrilla around to replace the injectors and FP, when it may in fact be the ECU.

[20ESGUY]

The obd system uses the O2 sensor to monitor the "lean" "rich" condition. It actually reads the O2 sensor as "lean" - "center" - "rich" . The ecu uses the output voltage of the sensor to determine that. I dont know what autozone's scanner is capable of, assuming it's not much, see if they can read the O2 sensor signal, if it's slugish to change from any of the three categories then it's probably an early sign of O2 failure, and yes the O2 actually floats between those three readings as the ECU adjusts the fuel mixture.

[Rumundo]

It's only got 35,000 miles on it. Is it normal for an o2 sensor to go out that early? I was talking to another guy about it, and he said it's got to be the o2. Where is the dumb thing, and about how much is it from a dealer, or can I get an aftermarket one? Thanks.

[Traveler]

It could be bad, but I'd check the fuel filter first. They definately only last about 30K miles or so.

[Rumundo]

I was told by Autozone that the fuel filter is in the gas tank. Is that true?

[NegatiZE]

Originally posted by Rumundo
I was told by Autozone that the fuel filter is in the gas tank. Is that true?

From what I have heard, yes our filters are in the gas tank. Supposedly supposed to last the life of the car.

[mazdamastertech]

p0171 lean bank 1 code. the mass air flow senser is contamined with dirt. if u are under a certain mileage it is covered by an extended warrnty by mazda. take it to a dealer to see if you qualfy. i have replaced quite a few.

[Rumundo]

Sweet. What is that magic mileage number?:D

[blynzoo]

Originally posted by NegatiZE


From what I have heard, yes our filters are in the gas tank. Supposedly supposed to last the life of the car. hmmm, the life of our car.
That would be a step up in technology. I assume that it will probably retain full effectiveness through about 50K, and remain effective until between 80-100k. That is my experience with N/A Miatas, at least.

[mazdamastertech]

7 years or 70000 miles

[Kooldino]

Originally posted by NegatiZE


From what I have heard, yes our filters are in the gas tank. Supposedly supposed to last the life of the car.

How hard is this to change?

[mazdamastertech]

there are two screws holding it in the intake tube. pull it out shine a flash lite in the holes to see if it has dirt on the wires. if so get a can of carb clean and spray it. u may need to brush it off with a towel or tooth brush. be very carefull, not to damage it. let dry and install.

[kokioki]

Very helpful mastertech, going to be trying this this afternoon, thanks!!

As for what to clean the sensor with, i heard electronic contact cleaner does a good job? Or is carb clean the way to go here?

[senna21]

Hello, first post here.

My girlfriends car has encountered the same problem. Idling poorly CEL on. We went to an AutoZone (we live in LA) and used their loaner tool program to get a code reader. Sure enough P0171 came up with nothing else.

So, I got a Haynes manual for the car (99 1.8L- 50,000 miles with NO prior problems) and began trouble shooting the areas that have been listed above. Before we got to the MAF the O2 sensor before the cat came back with a reading of .01-.07volts and the other one was reading .45 @ 3k rpm and then would jump to .8 when quickly revved to 5k and down to around .1 when quickly dropped to idle. Yahoo! We found our problem! :) Went online, and found a Bosh OE replacement for $125. Good price considering the Dealer wanted over $200 for theirs. Had it shipped, put it in in about 10 min, didn't fix it. (nervous) Then that same day Lisa (my GF) found this site and all things pointed to the MAF as I'd also posted on my normal site (MR2OC.com, I'm an owner of an 91 MR2 Turbo) to the P0171 code and most replies came back with the MAF. Ok, so I get some electronics cleaner and plan to clean it. MAF is easy to get to on this car and very easy to remove. I spray the crap out of it then gingerly take a q-tip and clean it. I'm all ready to put it back in when my right hand holding the MAF slips and my left, holding the q-tip, moves to steady it... I break the wire in the MAF. (flame)

Well, if it wasn't broken before it is now. We order one from MAZDA, get her a rent a car ($$$$ it's adding up now). Part comes in the next day (this morning) we immediately put it in... WOW seems to be running fine. CEL is still on, I unhook the battery for a minute, it goes out. We go to drop off the rent a car and her car dies on the way. Still idling rough, now rougher. But, no CEL.

Ok, we're done. Take it to the dealer. Bla, bla, bla, they call her... It's her intake GASKET! They say it's leaking. Now I'd heard a vacuum sound under the hood but I'd just thought it was the sound vibrating out of the intake. I'd checked all of the hoses, and as her car only has 50,000 miles on it they were perfect. Very pliable.

My question is how could an intake gasket go bad in such a short time!?! I'll try to tighten it down this evening and see if that improves the situation.

MAZDAMASTERTECH, is there any good way to test it to find out if it's bad? They want $400 in labor to do the job but, I'd rather do it myself. I'm very good at turning wrenches (but, I'll admit I'm more than embarrassed at not diagnosing this) and this should be a no brainer in comparison to working on my MR2.

We'll be posting pics of the surgery if/when it's done.

[Shane5425]

i hate that code, i get it all the time, its the maf, a cai will do that to the 1.6l, to much air and the maf cant compensate enough fuel for the air, i replaced the o2 , same problems, replaced the maf, fixed it, the maf gets dirty, messes up..

its 100 bucks for a remaned unit from mazda

[BlkZoomZoom]

Intake manifold gaskets are a pretty common thing. It isn't that hard to replace just alittle time consuming.

The easiest way to diagnois is with the car running at idle pour some water where the intake manifold meets the cylinder head. If it makes a gurgling noise and/or the idle changes you will know its bad.

[Shane5425]

Intake manifold gaskets are a pretty common thing. It isn't that hard to replace just alittle time consuming.

The easiest way to diagnois is with the car running at idle pour some water where the intake manifold meets the cylinder head. If it makes a gurgling noise and/or the idle changes you will know its bad.

spray carb cleaner there, if it idles smooth for few secs thats where the air leak is.. thats another way besides, water..

[Marik123]

Where is the intake manifold gaskets? I might have to check mine out too. Its doesn't have any CEL, but I do hear a puzzzzz sound when the car is idling. Sounds like something is leaking.... Is there any spray you can buy to seal it up instead of replacing it?

[jster28]

take the maf and spray brake clearner in it to clean out the maf. Solves the problem. Thats what i did and havent had the problem since.

[Shane5425]

i do that every now and then, it helps and drys instantly..

[00ProtegeLX]

FYI.... the 2000 1.6L protege LX has a recall on the MAF scensor.... not just a warranty others models may as well I dunno

[Shane5425]

that is well, known 7 year warrenty on them..

[TampaSport20]

I have an extra 1.6L MAF for sale if anyone is interested....$50 plus shipping, guaranteed good....

FYI....Mazda 3's MAF is the same part# if you want a practically new one from the junkies