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Mass Air Flow Sensor Replacement
 
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Pelican Technical Article:

Mass Air Flow Sensor Replacement

Nick Czerula

Time:

1 hour1 hr

Tab:

$200

Talent:

**

Tools:

Flathead screwdriver

Applicable Models:

Mercedes-Benz E320 (2003-05)

Parts Required:

Mass air flow sensor, engine air filter, mass air flow sensor seals

Hot Tip:

Work with a cool engine and clear engine fault codes when done

Performance Gain:

Car will run well

Complementary Modification:

Replace engine air filter, inspect intake air ducts for cracks

A mass (air) flow sensor (MAF) is used to find out the mass of air entering a fuel-injected internal combustion engine. The air mass information is required for the DME to control and deliver the right amount of fuel to the engine. Air changes its density as it expands and contracts with temperature and pressure. In automotive applications, air density varies with the ambient temperature, altitude and the use of forced induction, which means that mass air flow sensors are more appropriate than volumetric flow sensors for determining the quantity of intake air in each cylinder.

The mass air flow sensor monitors air flow into the engine and creates a digital signal for the DME. Mass air flow sensors accuracy skews over time and can lead to fault codes or drivability problems. When replacing, inspect the plastic intake air ducts for cracks or dry rot. If the intake air ducts are faulty, replace them first and see if the problem you are having is remedied. An un-metered air leak downstream of the mass air flow sensor will set codes similar to a faulty mass air flow sensor. When you suspect a mass air flow sensor as the culprit for setting a fuel trim fault code, check when the fault code was set. You can do this using OBD II freeze frame data. Normally, a vacuum leak would set a fuel trim fault code at idle or very low engine RPMs. A mass air flow meter would usually set a fault code when you are driving, or a higher RPM. You can check your fault code freeze frame data using an OBD II scan tool, similar to how you would check for fault codes. In this tech article I will show you how to replace the mass air flow sensor on W211 models with a 6-cylinder.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Never work on your vehicle if you feel the task is beyond your ability.

Disconnect the battery. See our tech article on battery replacing.

Working at the engine cover (red arrow), pull off the two front air duct hoses (green arrows).
Figure 1

Working at the engine cover (red arrow), pull off the two front air duct hoses (green arrows).

To detach the ducts, pull them straight off the engine cover / air filter housing.
Figure 2

To detach the ducts, pull them straight off the engine cover / air filter housing. Then pull the front of the duct out of the radiator support and remove it from the engine. Repeat this step for each duct.

Lift up and remove the front engine cover.
Figure 3

Lift up and remove the front engine cover.

Then, pull the engine cover / air filter housing straight up to remove it.
Figure 4

Then, pull the engine cover / air filter housing straight up to remove it. The cover is held on by four metal clips that grab onto rubber mounts, with the front two shown (red arrows). The rear of the cover has two as well. Once detached, remove the engine cover / air filter housing from the engine. Remove the mass air flow sensor. See our tech article on mass air flow sensor removing.

With the cover removed, inspect the rubber seal (red arrow).
Figure 5

With the cover removed, inspect the rubber seal (red arrow). If worn or damaged, replace it.

Disconnect the mass air flow sensor electrical connector by squeezing the release tabs (red arrow) and pulling the connector straight out of the sensor.
Figure 6

Disconnect the mass air flow sensor electrical connector by squeezing the release tabs (red arrow) and pulling the connector straight out of the sensor. The top release tab is shown. There is another tab on the bottom of the connector.

Unclip the plastic MAF mount (red arrow).
Figure 7

Unclip the plastic MAF mount (red arrow). Lever the locking tab open when unclipping.

Remove the plastic MAF mount from the engine.
Figure 8

Remove the plastic MAF mount from the engine. Open the mount and feed it off the MAF sensor.

Working at the back of the MAF sensor, lever the retaining clip (red arrow) away from the sensor while pulling the sensor up in the direction of the green arrow.
Figure 9

Working at the back of the MAF sensor, lever the retaining clip (red arrow) away from the sensor while pulling the sensor up in the direction of the green arrow.

Remove the MAF sensor from the intake air duct.
Figure 10

Remove the MAF sensor from the intake air duct.

Inspect the seal to be sure it is not worn or damaged.
Figure 11

Inspect the seal to be sure it is not worn or damaged. If replacing or reinstalling, be sure to line up the tab on the seal (green arrow) with the hole in the duct (red arrow). Install the new mass air flow sensor into the duct. If the seal gives you a hard time going in, apply a small amount of dish soap to the seal. It will slide right in. The soap will not damage the seal. Check the vehicle for fault codes. See our tech article on reading and clearing fault codes. Then test drive the vehicle and confirm that the engine runs well.

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Comments and Suggestions:
Appoi Comments: Hi;..good morning. ..I have left amessage on your mail box that I want to buy a Air mass sensor for my Mercedes E200....W211...dual fuel.Petrol &..Cng....Year of manufacture -2006.......Chasis number - WDB 2110422A970530.......Engine number is....27194130767047.....plese send me the link for me to make the order..Thanks waiting for your reply.....Regards..Balan
September 25, 2016
  Followup from the Pelican Staff: E200 doesn't show up for me in US. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Ben Comments: Looking to buy....air flow senser....for E200.....my mercedes....is dual...Petrol & Cng... ngt ...its a 2006 model......WDB is...2110422A970530.....& ...Engine number is....27194130767047......if you have this part pls email me....tnx regards.....Ben
September 22, 2016
  Followup from the Pelican Staff: I’m not the best with part numbers.

Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
gk Comments: thank you great instructions
September 1, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 

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