Not your average SES P0171, P0174 error code...

[mdadrass]

Hello all,

Let me begin by thanking all of those that contribute to this fine forum as the information posted here is worth it's weight in gold.

My Problem...SES P0171, P0174 codes coming up on my 2001 4.4i (4/2001 prod) X5 with 59K miles. Here are my issues other than the codes:

1. Low gas mileage (3-4mpg worse)

2. The car stalled twice a while back at very low idle but not since.

3. lower power at full throttle

I checked the 2 vent hoses on the top connected to the oil separator for cracks but could not find any although they really felt pretty mushy and beat up.

After searching the threads extensively I've come up with these solutions:


1. Check/Replace Vent hoses that connect to the oil separator

2. Replace Fuel Filter

3. Clean/Replace Mass Air Sensor

I'm looking to sell the car soon so I really just want the SES light off and done with.

Am I missing anything here or any other suggestions?

Thanks in advance!

[lo_jack]

I would check your plugs for sludge, then probably go ahead with items 1 & 2.

[mdadrass]

Thanks for the response. Just to clarify, are you referring to changing the spark plugs?

[The Cleaner]

The computer is seeing "LEAN" but it's supplying to much fuel so don't start with the fuel system, you are obviously getting fuel. I would start at the MAF then check the O2 sensor voltage, check for intake leaks in the boot (After the MAF), check for intake manifold leaks, front and rear cover are a good place to start.

[RichiRich]

I also ...just got pinged with these codes...

I have done it all....

I also am burning through gas like you would not believe...

You will have many opinions here with many variations...

I am going with a new MAS.

Rich

[mdadrass]

There just seem to be SO MANY places after the MAF to look for an air leak, which IMO is most definitely the problem in ADDITION to a bad MAF (which causes ususally causes engine bang running rich error codes if I'm not mistaken) or not enough fuel (causing engine to run lean).

My guess is that the stealer would have a FIELD DAY with this issue and repairs would be well over a grand.

Has anyone come up with a DIY solution to detecting an air leak in the induction system?

[01 BMW_X5]

If it was me hunting down a suspected air leak, I would spray carb cleaner/engine starter fluid and observe engine idle/rev.

Worked for me in the past.
Old school, but it works.

[mdadrass]

Thanks for your replay and yes, that is a tried and proven old school method that I used to do back in the day as well.

I'm reading on several older threads that the on board computer will make adjustments when spraying carb cleaner at leak points making engine idle/rev change undetectable. I'm going to try it anyway before I start ordering parts...

[4point4eye]

I recently had Mass Airflow Sensor and a Cam Position Sensor replaced in response to an intermittent SES light.

4point4eye - 2000 X5 4.4i 106,000 miles

[01 BMW_X5]

Originally Posted by mdadrass

the on board computer will make adjustments when spraying carb cleaner at leak points making engine idle/rev change undetectable.

When I see it, then I will believe it...