Obd2 code P0171 and P0174

[jreyes19]

I just got these codes while driving and after doing a little research they say it is o2 sensor finding that my fumes are too oxynigated,

Had any one ever recieved these codes and what are your experiences thank you



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[danewilson77]

These are the most common codes found on E46. You may also have a vacuum leak, causing it to run lean.

I would inspect upper/lower intake boots first (free).

[webster]

this post might help:

P0174/0171 is a general system too lean code, which means the engine is either getting too much air or not enough fuel in the mixture. There are a number of reasons you can have that code and they need to be tracked down.

The most common reasons for this code is either a vacuum leak somewhere in the air intake past the MAF sensor, or clogged up fuel injector(s), or a clogged up fuel filter or a weakening fuel pump

[danewilson77]

I thought fuel issues made it run rich (rich codes)?

[webster]

here's a great post i found from bf.c

If you haven't already, read the e46 wiki carefully (link at the top of page). It's a great resource. VANOS is BMW's variable valve timing system. The DISA valve is a device that controls air flow in the engine. Perhaps Bluebee can weigh in with some specific info on what the DISA does if you're interested, but the point is that they are completely different things. What I know about the DISA is that there is a plastic pin in the center of the butterfly valve that can get brittle and crack over time, causing the butterfly valve to flop around. This is what caused my car to throw P0174 and P0171 codes. Fortunately, the DISA is easy to replace. Unfortunately, the part is about $200.

So, I'd say your plan should be to go down the list of common "running lean" culprits. Start with your intake boots -- might as well just replace them anyway if they are original. Next, buy a bottle of Techron injector cleaner, and try that, or give it the old "Italian tune-up," as I heard it once called here -- take your car for a spirited drive, occasional high revs being the key, to try and clean the junk out. (These cars should be driven hard once in a while, it's good for them.) While your intake boots are off, carefully remove and inspect your DISA valve -- see if the butterfly valve is flopping around, if so, replace it. While all that's out, get a flashlight and little mirror, and check your oil separator -- if there's oil all over it, replace it. Check the hoses running to that, they become very brittle over time and can develop cracks, leading to vacuum leaks or oil leaks. The CCV is a pretty tough job, but it's a worthwhile DIY, and it is an extremely common failure point on our cars. In fact, if you're doing your intake boots and DISA, you might as well replace your CCV while you're at it if it's never been replaced before. The oil separator is about $50, and the four hoses of the apocalypse are about $15 each online. Also clean your MAF, throttle body, and idle control valve while you're at it. There are DIYs online for all these jobs -- it's good call to avoid paying someone for this, they'll charge you an arm and a leg for most of this work.

It's also worthwhile to buy a code reader while you're at it (I just use a cheap Autozone OBDII reader) to clear your codes and take it for a test drive to see if any codes come back.

and this thread:

http://www.zhpmafia.com/forums/showt...t-code...p0174

[jreyes19]

Ok guys
Here is the current verdict
After changing my valve cover gasket, I checked the lower intake boot and found that it was cracked and with just a little force my a finger went right through the crack I sealed the cracks with high heat silicone sealant. Also the smaller tube (i think it is a air reliever tube) broke right off. So I just put a larger tube on top of the old tube as a fix.

I reset the light and it has yet to come back on so I assume those were the problems, now I need to buy a new lower intake boot


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[zj96sc]

Nice work. Pretty common failure for those codes.

13541438761 upper - $22

13541438759 lower - $11

[danewilson77]

These are the most common codes found on E46. You may also have a vacuum leak, causing it to run lean.

I would inspect upper/lower intake boots first (free).

Yup. Duct tape also works great until you can get new boots.





Sent from Williamsburg, VA USA

[jreyes19]

UPDATE!!!
even with the sealant fix the light still came on

well i replaced the lower intake boot, and the lights came on again

I will go in and check the upper intake boot (should have checked it earlier, i assumed it was the lower one when i saw the cracks)

,but can it be anything else?, i have read it could be fuel pump, ccv, possible o2 sensor any input on these

also when should i replace the o2 sensors?

I dont like this light!!! lol

[kayger12]

Make sure you have the lower hose seated properly with the tab in the groove.

I've seen a lot of reinstalls over the years where it wasn't mated up perfectly and continued to throw a code.

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