Xoutpost.com - P0171, P0174 resolved

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I had the same codes P1158, P1160, P0171 and P0174 for about a year. Maybe a dirty MAF sensor. Have you tried cleaning it? Spray the cleaner where the connector goes too and shake it until it gets inside the sensor. Then as you will notice there is an arrow on the sensor itself. When you put the MAF sensor in, make sure that arrow when you turn it to lock it in the MAF slot it points towards the engine (not towards the Air Filter). 2 of my friends and including me had this same mistake. Cleaned it but not noticing that the MAF has to be placed correctly or if not it will trigger those codes. I did this and did a reset. Drove the X for about 550 miles now and no CEL.

Just saying make sure about that arrow points towards the engine when putting it back. I had it backwards for the first 3 times i cleaned it and it would trigger the CEL. Hope this helps.

Quote:

Originally Posted by boywondergq1 (Post 738517)

So for those following my story, I should note that right after I replaced those two hoses and started it up the first time a puff of black smoke came out of the exhausts. I wonder what got in there after replacing the hoses to cause that, or if that incident messed up the O2 sensors.

My 'CAT not ready' finally went to 'ready'. So far so good. A few days later, 'EVAP not ready' finally came ready as well after about a tank of gas worth of driving for 2 weeks. Shortly thereafter, some new codes appeared:

P1158 and P1160: Fuel Trim Adaptation Additive Low (Bank 1) and (Bank 2) <-- (from what I've googled)

Does this mean the 2 oil separator hoses I replaced did something? I've read that the Fuel Trim Adaptation 'adusts itself' over time. Do I need more time? Do I clear these and wait again?

Hmm. Mass Air Flow sensor? Yeah, called BMW and they want $695 CAD for a new one. I haven't had much luck with cleaning these.

I think I'm ready to throw in the towel on this one.

Great, thanks I'll try that. Worst thing that can happen is I mess up my MAF and get another one on the internet for 1/3 the price of what BMW wants!!

You're Welcome! Ohh man i was so tempted to buying a new MAF too. I actually just did this a week ago and noticed that damn arrow pointing towards to the air filter. i was like what the heck is this arrow for!? I did what i told you and after that reset my car (Unplugging the negative connector on the battery since i didn't have a OBDII scanner for about 10 mins) and bang drove the car so far no CEL.

Quote:

Originally Posted by boywondergq1 (Post 738517)

I've replaced the oil sep hoses too. I was still getting P0171 and P0174 codes that would not stay reset. I cleaned the MAF, but that did not change the outcome.

Then I ordered a new MAF online. The new MAF worked fine, giving a smooth idle. When I checked the active codes, the P0171 and P0174 were inactive. I cleared them to reset the CEL and it's been all clear for 4 days.

Try cleaning the MAF and if that doesn't work, you could try to swap MAF's with someone who has the same engine to troubleshoot, or just bite the bullet and order a new one.

Quote:

Originally Posted by mysweetx5 (Post 740236)

I WHICH I COULD LOCATE THIS PART ON MY ENGINE COMPARTMENT, BY THE WAY I WOULD BE ABLE TO FIX THAT EASILY AS MENTIONED!

the 4.4i engine does not have that part
6 cyl engine has it

Okay, I'll save some people some time. After chasing this down I'll give an abbreviated account of what was discovered since I'm typin on my iPhone right now :)

1. Took it to the dealer - they diagnosed it as a leaky manifold gasket; wouldn't tell me which one but I was quoted $1,800 CAD + tax to fix it. After picking myself up off of the floor I didn't ask questions, I got it out of there and took it to an independant BMW specialist shop.

2. They diagnosed it as, get this, a STUCK OPEN THERMOSTAT and a failed MAF SENSOR!!! They changed both, at a considerale cost as well mind you ($1,200 CAD + tax) but I was shocked that their diagnosis was correct and solved the problem.

I've learned my lesson about BMW mechanics, and am now in the market for a newer X3, X5 or GLK 350 WITH EXTENDED WARRANTY.

Seriously, I thought it was only the paranoid people who suggested extended warranties and to be honest I never subscribed to that camp but in the case of aged German vehicles it is imperitive.

Hope this helps some people; iv been chasing this down for 2 months and I'm so done.

I have this problem, iv changed the 2 vent pipes as they were soft ant ripped apart, it runs a lot smoother but still have the engine light on!

There are videos on YouTube on how to repair the DISA valve as well.