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Tumble Flap Position Sensor Replacement
 
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Pelican Technical Article:

Tumble Flap Position Sensor Replacement

Steve Vernon

Time:

2 hours2 hrs

Tab:

$50 to $100

Talent:

**

Tools:

T-30 Torx driver, small flathead screwdriver

Applicable Models:

Mercedes-Benz C350 (2008-14)
Mercedes-Benz GLK350 (2010-14)

Parts Required:

Tumble flap sensor

Hot Tip:

Be prepared to move things out of the way

Performance Gain:

Working variable resonance intake

Complementary Modification:

New air filter

The Mercedes C350 has a variable resonance intake manifold. This manifold can switch over from long intake runners to short intake runners by utilizing switch flaps and tumbler or flap shafts. There are two shafts, one on each side of the intake manifold. If you are getting error codes from the variable system, one of the first things you should check is the tumbler flap sensor for failure.

Both sensors are located at the rear of the intake manifold. While replacement in theory is easy I have never been able to simply access the T30 Torx screw that holds the sensor in place and remove it without having to move the wiring harness and fuel rail. If you have small enough hands that you can access the sensors then you do not need to remove anything. If you have hands larger than a ten year old you may need to remove other components.

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows).
Figure 1

You will need to remove the front (red arrow) and rear (yellow arrow) engine covers along with the air ducts (green arrows). Please see our article on engine cover removal for additional assistance.

Both sensors are located under the wiring harnesses and fuel rail (red arrows).
Figure 2

Both sensors are located under the wiring harnesses and fuel rail (red arrows). If your hands are small enough to fit in there you can remove the T30 Torx screw and remove the sensors. If you hands are not small enough to fit, please see our article on fuel injector replacement for the steps needed to move everything out of the way.

This photo illustrates the sensor and connection on the right side of the manifold.
Figure 3

This photo illustrates the sensor and connection on the right side of the manifold. The small tab faces the rear of the car. You need to insert a small flathead screwdriver and lift the tab (red arrow).

With the tab lifted gently squeeze it back and pull the connection (red arrow) straight up and off the sensor (yellow arrow).
Figure 4

With the tab lifted gently squeeze it back and pull the connection (red arrow) straight up and off the sensor (yellow arrow).

Make sure to clean the area around the sensor and use a T30 Torx to remove the single screw holding the sensor in place (red arrow).
Figure 5

Make sure to clean the area around the sensor and use a T30 Torx to remove the single screw holding the sensor in place (red arrow).

You can now pull the sensor up and out.
Figure 6

You can now pull the sensor up and out. The sensors can only be installed in one direction when reinstalling.

This photo illustrates the left side sensor with the fuel rail and harness removed (red arrow).
Figure 7

This photo illustrates the left side sensor with the fuel rail and harness removed (red arrow). Removal is the same as the right side. Installation is the reverse of removal.


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Comments and Suggestions:
Joe Hru Comments: Tumble Flap Position Sensor Replacement
Question: What is the testing method for tumble flap sensors to determine if it is faulty?
August 24, 2016
  Followup from the Pelican Staff: You can use a scan tool to monitor desired verse actual flap position. Or monitor the flap sensor signal using a lab scope and see if changes along with flap position. - Nick at Pelican Parts  
Omie Don't You Know Me Comments: Sorry about the typos... Here is an easier one to read:

I can tell you that since I currently am replacing my entire intake manifold not just the flap sensors, the steps shown, the connectors, the screws, as well as the procedure to remove these sensors off of a 2008 W204.054 C300 Sport RWD 3.0L 272.947 is identical to what is shown here.

The only part I'd disagree with is if someone has "small hands"... To be able to access these sensors whether to remove them or to simply unplug them as part of the process of replacing the entire intake manifold, and to do so without unbolting the wire supply ducts thereby allowing you to pull the looms of wires up and forward, as well as possibly removing the fuel rail to expose the sensors, your hands would have to be extremely small to get anything done there...
March 19, 2016
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 
Omie Don't You Know Me Comments: I can tell you that since I currently am replacing my entire intke manifold not just the slap sensors the step, connectors, screws, as well s the procedure to remove these sensors off of a 2008 W204.054 C300 Sport RWD 3.0L 272.947 is identical to what is shown here.

The only part I'd disagree with is if someone has "small hands"... To be able to get access these sensors whether to remove them or unplugging them as part of the process of replacing the entire intake without unbolting the wire supply ducts thereby allowing you to pull the looms of wires up and forward, as well as possibly removing the fuel rail to expose the sensors, your hands would have to be extremely small to get anything done there....
March 19, 2016
  Followup from the Pelican Staff: Thanks for sharing your installation process and experience. These type of comments add so much to the Pelican tech community.
- Nick at Pelican Parts
 

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