# Help Please! P1161,P1159, P0174 ans P1071



## Bkack_Knight (Sep 11, 2007)

Hi guys, 
I have 2001 740il and the check engine went on and when I ran the scanner I got these codes:
P0171 System too Lean (Bank 1) 
P0174 System too Lean (Bank 2) 
P1159 Fuel Trim Additive Bank 1 High (BMW) 
P1161 Fuel Trim Additive Bank 2 High (BMW) 

Do you have any idea what the problem would be?
Any help would be appreciated .


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## crewdog843 (Mar 15, 2006)

The SES (Service Engine Soon) and CEL (Check Engine Light) both illuminate for emissions related problems. First question any service writer would ask you is: Is the car running all right?"

If the car is running all right, they will tell you to schedule an appointment at the next available time. In other words, the emissions related problem is not serious enough to warrant leaving the car for further diagnosis. My 2001 did the same thing and I got that question. The light went off and back on a couple of times before I was able to bring it in (roughly one week) but the car ran beautifully.

When I brought it in, they found a cam position sensor bad and replaced it under warranty. No lights since then, and that was over a year and a half ago.

Now, replacing a cam position sensor on these cars is very easy, and with the proper tools and time, you can do it yourself. I believe there is a left and right sensor (there are two) on this car, so you might want to shop around to find the least expensive (including shipping) or just buy one or both from your friendly local dealer. To find out how, check www.e38.org www.autohausaz.com is competitively priced but shipping may be expensive. www.bavauto.com is also a good source of parts....do your homework.

Is the car stumbling when you try to start it, does it die, or almost die at a stop light. These are signs of a failing MAF (Mass Air Flow sensor). Another possible culprit might be the O2 sensors (there are four of them, 2 pre and 2 post catalytic converter).

I'd go for the cam position sensors first.

jake


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## Bkack_Knight (Sep 11, 2007)

Thanks Jake for your quick respond.
Yes, when car is in ideal every 30 seconds it sounds dying and starts shaking (a little bid). It happens sometimes at stop signs as well.
Should I start with MAF sensor or cam?
Thanks


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## crewdog843 (Mar 15, 2006)

MAF.

That having been said, don't replace the entire MAF, only the sensor.

Check with www.bimmerforums.com and do a search on MAF...you should get multiple hits, especially during the last couple of weeks. I don't think you can just buy a BMW MAF sensor by itself, but the ROVER (I believe it is) MAF crosses over to the BMW with no modifications. And....it is a DIY as well. www.e38.org says you can clean the sensor, but it is not infallible. I have heard of few who have successfully done this.

The cam sensor will allow your car to run very well but will illuminate the light.

jake


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## crewdog843 (Mar 15, 2006)

Google BMW MAF

Second article is entitled "Tech" Read.

jake


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## Greg64 (Dec 21, 2008)

I tried cleaning mine, no good. Replaced it and the codes went away. Good ol' Actron. I am now getting ready to replace the oil separator hoses that are located at the top rear of the engine. I took off the cover and looked in the back to find that both hoses were like gum. The top hose was cracked. Ordered new hoses from PartsGeek. 1/2 off what the stealer wanted. I'll post pics tomorrow to show you where they are.


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## crewdog843 (Mar 15, 2006)

While working on the OSV, take out the orange diaphragm and replace it, it'll be about time for that year. Also, check the hoses for the heater leading into the firewall...if they look bad, cut em off and replace them.

jake


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