Diverter valve?

ASHOK SAINI

MEMBER
2012 BMW X3
2.0L
4 CYL
4WD
AUTOMATIC
160,000 MILES

The car listed above is a 2013. 120308 Charge air pressure control, plausibility pressure too low fault. Could it be related to Diverter valve or Transmission filter clogging? Other hoses and pipes are good, including vacuum pump, and solenoid switch.

3 Replies

JACOBANDNICKOLAS

MECHANIC
108,328 POSTS

Hi,

The purpose of the diverter valve is to redirect boost away from the intake when it isn't needed, so no to the transmission and yes to the charge air pressure control. However, I don't feel that is what would set this code.

The code would likely be the result of an issue with the boost pressure sensor, the wastegate valve is stuck open, a vacuum supply to the wastegate valve, an electrical issue, or a vacuum issue in general.

I need to know the correct engine size. Did you mean a 3.0L engine because a 2.0L wasn't an option?

If it is the 3.0L, I attached the description of the code below and possible causes. Take a look through them and let me know if they help. Additionally, if I have the wrong engine size, let me know.

Take care,

joe

See pics below.

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Tuesday, July 12th, 2022 AT 10:01 PM

ASHOK SAINI

MEMBER
32 POSTS

Hi Joe,

Thanks for your reply, mine is 2013 BMW X3 2.0-liter engine. Engine seized last year so I replaced and installed a used 2015 engine (which is similar) in November 2021. Lean Fuel code was eliminated by replacing new turbo intake charge pipe, the only problem is code 120308 Low boost pressure plausibility pressure low. The attached scan report was having a leak and was fixed by using the resin glue on the leak site on the vacuum tube in the engine bay, also changed vacuum pump, and boost solenoid switch as before there was oil accumulation in the vacuum reservoir now upon starting it smokes but after 30 sec or so it's okay, but under the muffler area the is a flap flutters and makes noise when it starts but stops when I accelerate with pedal or drive the car.
I posted this problem before on your site and I was suggested to check clogged transmission filter which I didn't do, as I feel perhaps diverter valve may need a replacement or there is definitely just one part needs replacement then all should be okay, but I do not know which. My wild guess included Spark plugs, coils, diverter valve or the seal at throttle intake pipe which is a O ring stays inside the throttle charge pipe. I want your help in narrowing down the problem to just one part which is activating Transmission malfunction light which indicated that I can drive moderately but take to Repair center. BMW is a big rip off, I want to do it myself.
Thanks for your valuable time and support.
Regards,
Ash

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Wednesday, July 13th, 2022 AT 5:31 PM

JACOBANDNICKOLAS

MECHANIC
108,328 POSTS

Hi Ash, thank you for the update. However, I have a question. Is the transmission malfunction light where your concerns are? Are there any codes related to the transmission? Have you scanned the can-bus? Also, did the vehicle originally come with a 3.0?

Here is a link showing how to scan the can-bus. CAN simply stands for controller area network. Basically, all the computers/modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them. Take a look.

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

If you haven't done this, it could be very helpful.

The idea that the engine size was changed may create an issue, I'm not sure what was done with the electronics to make it work. The original powertrain control module was for a different setup. Was the original transmission used or was it changed?

Let me know as much as you can. Sorry for all the questions. Also, I can't even tell you how many times I've seen the charge air pipe crack or break on these vehicles.

Take care and I'll watch for your reply.

Joe

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Wednesday, July 13th, 2022 AT 9:46 PM