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Discussion Starter · #1 ·
Hey I was wondering if anyone had any clue on why I keep getting the CEL for P0299 for my 2015 Mercedes CLA 45 AMG. It goes on and off randomly. I had the Turbo and lines pressure tested by the dealership and they came out okay. I even had the turbo boost control valve replaced. The car would go into limp mode or lose a decent amount of power whenever the light comes on. Anyone got any suggestions on what I should be looking at.
 

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Welcome to the CLAForum Rajmahal :)
Tell us more:
*Did you buy your CLA as a MB Certified Pre Owned from an MB dealer?
*How long have you had it?
*What are the other codes you found?
*What city are you near?
*Your mileage?
 

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Discussion Starter · #3 ·
Welcome to the CLAForum Rajmahal :)
Tell us more:
*Did you buy your CLA as a MB Certified Pre Owned from an MB dealer?
*How long have you had it?
*What are the other codes you found?
*What city are you near?
*Your mileage?
:
I bought the car new in january 2016 with 32 miles on it. Ive had it since then. I daily drive the heck out of it so it has around 126,000 miles on it right now.
I mainly get the P0299 code but occasionally a p0102 code would appear. I reset the code via a bluetooth obd reader but it appears every other day or so.
The car currently has a weistec mid and down pipe, air intake,blow off valve and tune. I had the systen pressure tested but the mb dealership found no leaks. They replaced one part but the problem still occurs. Ill post extactly what they wrote when i find the service paper.
 

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OK that will help - we will see if a member can offer clues for you.
 

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Discussion Starter · #6 ·
Heres what the dealership wrote and found during their inspection.
The problem still persists even after.
The code will randonly appear and then i would clear it and would appear again after a few days or hours.

"

Verified check engine light is on. Connected SDS and performed quick test. Found code p029921 The boost pressure of turbo charger 1 is too low the signal amplitude is less than the minimum amplitude processed code. Removed intake housing and smoked intake system and check for leak. No leaks found. Checked turbo and found good. Checked actuation at turbo diaphram and found performing as designed. Pulled vacuum at turbo diaphram and found hold vacuum. Checked duty cycle for boost pressure positioner and found it is below spec.
Recommend to replace.
Removed and replaced boost pressure positioner. Connected sds and cleared fault codes.test drove vehicle. Ok

Part number 00-153-18-00 pressure trans "
 

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Discussion Starter · #8 ·
It appears randomly. Sometimes under acceleration or just at constant speed. Whenever i reset the cel it usually takes anywhere from 5 or 8 hours to a 2 or 3 days for it to appear again. I feel a loss of power either to something mechanical or the car goes into limp mode whenever the cel is on. And i currently have no way monitor the boost pressure.
 

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Could be a small crack in one of the vac lines causing this.
 

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Discussion Starter · #11 ·
Seems to me to be the actuator. The car is inconsistent with boost pressure. Some days im getting full boost some days only 5 or 6 psi woth no cel at times.
Just ordered the actuator so ill keep yall updated.
 

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Seems to me to be the actuator. The car is inconsistent with boost pressure. Some days im getting full boost some days only 5 or 6 psi woth no cel at times.
Just ordered the actuator so ill keep yall updated.
Yes keep us posted and good luck. It doesn’t hurt to replace the actuator as it is not expensive. It very well may be shot and not closing properly in order to build the proper pressure.

If it was a vacuum line leak your vehicle would stumble and not be able to idle properly. Any other type of boost leak, it would be audible and you would definitely be able to hear it under the hood.

You should invest in a vacuum/boost gauge. They have electronic gauges that connect plug and play via OBDII and use your sensors to display the vac and pressure.
 

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...And also eliminate the exact cause.
 

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Those lines don’t build pressure but you’ll want to fix them. It’s a common issue on the 45 due to how the engine cover sits so closely. It’s an easy fix, just take the cover off and where it snaps into place, take the Mount off and space them with a few washers so the when you snap the engine cover back on its raised a bit so it’s not forcing those lines to touch the aluminum. You’ll want to check to see if it’s just the shielding that got burned or if it went through the rubber hose.
 
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