Found cause of P0172 & P0175 DTC's

[Harley Monster]

Welcome aboard Pdabbs,

If you are an active DIY kind of person and it sounds like you are I would recommend you purchase the BMW X5 Service Manual by Bentley Publishers.

it is not a cheap book, but it will pay for itself the first time you use it. I put it off way too long and now that I have it I would not give it up. You will see it referred to many times on this forum. I purchased mine through Amazon.

With that said, the replacement of the Y duct is difficult only because the clamps are so hard to get to from either above or below. Once I figured out to use a nut driver (8mm) the job went smoothly. Once the clamps begin to loosen apply only the smallest amount of pressure, just enough to keep the nut driver on the clamp. If you put too much pressure on the nut driver the clamp will rotate out of range then you will have to rotate it back to the original orientation and start over.

To get access you will need to take off all the ducting leading to the Y duct. Start at the intake cover over the radiator, pull the center plug up on the 4 reuseable rivets that hold that cover on and it comes right off.

What I did was lay the parts out in the order I took them off along with each set of fasteners. Unplug the Mass Air Flow Sensor and loosen the clamps and remove it. I also took out the air filter box for more access and it is a good time to cliean it out and clean beneath it, replace the filter if it needs it.

There is one more set of clamps futher down the intake, loosen those and remove the last piece of the intake.

There are two vaccuum lines that plug into the Y duct, carefully remove those with a back and forth twisting motion and they should come right out.

All that is left is to loosen the large and small clamps holding the Y duct to the Throttle Valve and to the Idle Control Valve then pull the Y duct off.

The assembly is just the reverse.

I have had no further codes or SES light since I replaced this Y duct. Mine had a large tear on the bottom of the bellows portion of the small duct that goes to the Idle Control Valve which was only be visible with a flashlight and mirror.

Best of luck.

Harley Monster

[pdabbs911]

Thanks a million Harley Monster. Yes I am a DIY person. I like learning which is the primary reason for the DIY stuff that I do (not to mention it is much cheeper). Thanks again for the help and I will let you know how it turns out. I will be getting the manual as well.

[Harley Monster]

Best of luck, you will not have any problem with this job if you are patient. If you can get into the clamps on the Throttle Valve and the Idle Control Valve the rest of it is a snap.

This forum has saved me so much money...thousands. You will quickly learn to come here first when you have any kind of problem with your X5. There are many very experience technicians on this site that are more than happy to help you out.

What year is your X5 and how many miles. Let me know and perhaps I can give you some areas to watch so you can take care of the problems at YOUR convenience. Like I tell people, I like working on cars, but I like to do it when I want to not when the car demands it.

If you have a problem, post or send me a PM as I check my email many times a day for other commitments.

[pdabbs911]

I received the intake boot in the mail yesterday. It took me about 2hrs to install and that included the time spent digging out the socket that I dropped twice. My socket for the clamp was 6mm. I also removed the bracket that is just to the right of the idle control valve. Doing this really helped gain access to that last clamp. Local mehanic quoted me $300 on this job, so I made $150/hr yesterday. Nice!!!

I have a 2002 X5 with 133K. Just bought it last week. I think it is in pretty good shape and seems to have been well maintained, but any heads up on what to watch out for would be greatly appreciated. I was thinking about tackling the O2 sensors mentioned above at some point as well. I need to search around for some good pics of that part first, just to make sure I am taking the correct part off. 1st thing on my list is oil change and I was considering a tranny fuild/filter change since I don't know when those where done last.

Thanks again,
PD

[Harley Monster]

Pdabbs,

If you spend much time on this forum and I think you will if you have an X5, you will find that the cooling system is probably the weakest system in the car, not only X5's but nearly all BMW models.

Check your records to see if the cooling system has been overhauled, if not at your mileage this should become a priority. These systems begin to fail around 70-80,000 miles and up.

My X5 had a catastrophic failure of the water pump at 98,000. Do an Advanced Search in this forum using the Search this Forum button in the top right hand corner, search by User Name: Harley Monster and look for my post: Water Pump Catastrophic Failure. In my post you will see what happens when you ignore the warning signs of Low Coolant or hear a chirping noise from the front of the car at idle.

If your cooling system has been overhauled you are home free.

If it has not been overhauled plan on changing everything in the cooling system.

I just did my daughter's 3 Series with around 150,000 miles and her cooling system had never been touched. See kept getting Low Coolant warnings.

I replaced the water pump, thermostat housing and thermostat, all idlers, new belts, all new hoses, radiator, fan clutch and expansion tank .

In the overhaul of the cooling system I did not replace the heater hoses nor on my daughter's car though now I wish I had as I now have a heater hose leaking. When I did the Y Duct replacement I believe the movement of the radiator hoses coming out of the radiator upset the O ring in the end fitting and it has begun to leak.

I now have all the heater hoses on hand and plan on replacing all of them (4) in the next few days.

Other than that the only other problem I have had was the Cam Sensors, I replaced both and this is an easy to do DIY project. This is another common failure.

The O2 Sensors are very easy to get to on the 3.0L engine, look on the Passenger Side of the engine on top of the headers and you will see both the O2 Sensors plainly visible sticking up like sore thumbs. I have mine on order, but have not received them yet. If you can't find them let me know and I will post a photo for you.

Our cars are of the same vintage and mileage, mine is a 2001 3.0L with about 118,000.

The X5 is a GREAT car, but like any performance car it takes some care to keep them in top running condition...but that is part of the fun!

Best of luck,

Harley Monster

[pdabbs911]

I will be on the alert for a "chirping sound". That looks nasty. I think, I may be in good shape. I took the X5 to a guy, I trust and like for his opion, who works on these for a living. He said, " the radiator has been replaced, that is good". Now I know what he may have been referring to. He looked it over really good and said that it looked to be well maintained. I am going to give him some business initially with oil change and maybe a tranny filter change to return the favor. But I plan on doing the oil changes myself in the future. I think I found the O2 sensors yesterday. Only 2 of them right? I thought maybe I read that there where 3 of them? I really have no previous history of maintenance, so I really want to do some these things just so I can start a new history record. This will be my wifes daily driver so I will alert her as well.
Thanks again,

[getgoals7]

i also had to replace that part a few weeks a go.

[Harley Monster]

I would agree, if the radiator has been replaced there is a good chance other parts in the cooling system have also. Just be alert to the "Loss of Coolant Light", that seems to be the foreteller of problems to come. If you get it then begin a close inspection instead of just adding fluid and hoping for the best. The coolant would going out someplace, check water pump weep hole and for cracks in the expansion tank. My daughter’s 3 Series had both.

Before you change the Tranny Fluid do some reading and make your own decision.

BMW recommends 100,000 miles, but many who have change the fluid then begin to have trans slipping problems.

I asked "my tranny guy" who I trust about it and he said there is some merit to NOT changing the fluid in a high mileage car. The problem as he explained it to me is that as the clutches wear the fluid becomes more "abrasive" and keeps the high mileage trans from slipping. When the fluid is changed it is "slipperier" and hence the slippage.

I made the decision NOT to change my fluid, whether that is right or wrong is debatable. I suggest you do searches and read on this forum as well as others before you make your decision. My daughter’s 3 Series has a little over 150,000 miles and has never been serviced. Trans overhaul is very expensive on the X, it seems like you take a gamble either way you go.

As far as the Oxygen Sensors there are actually 4, 2 pre-Cat and 2 Post-Cat, you only need to replace the 2 Pre-Cat sensors because those two send signals to the fuel injection system. The two Post-Cat sensors are only there to trip the SES Light in case the fuel injection system has a large emissions error, they have nothing to do with tuning.

[pdabbs911]

I have read some of the same thoughts as you over on the full size bronco site about the high mileage trannys. Its like you said a "gamble either way". I am not completely sold on the tranny service so I may wait a little longer. I well definately question my mechanic guy and search this site as well. If I look at my automobile owning history, the tranny and coolant problems have seem to be my gremlins. Ha Ha gotta laugh about that.

I am going to do the O2 sensors for sure. It looks way to easy not to go ahead and do that service.

[FSETH]

Does anyone know the name of the duct that runs from the intake cover on the top of the radiator to the air filter box on an 02 4.4i? I can't find a part number, because I have no clue what it is called. Mine has cracked on the bend similar to how the OP's cracked on the boot.