Appendix “M” Mass Air Flow Sensor MAF Cleaning does it work?

Appendix “M”

Mass Air Flow Sensor MAF Cleaning does it work?

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My 1996 check engine light lit up. The Durametric software told me: - Mass airflow sensor not working. I called the local Bosch dealer and found out the part costs over $300. This led me to go through the exercise of cleaning the sensor even though at 80K+ miles I was suspect that cleaning the sensor would solve the problem.

I purchased CRC brand spray Mass Airflow Sensor  Spray Cleaner, removed the sensor from the car, and hosed off the sensor with it. Upon closer inspection, I noticed the actual sensor element located in the slot of the sensor’s stalk that protrudes into the intake air-path had a gray flat soot coating on both sides. I sprayed some of the CRC cleaner on some swabs and rubbed the element on both sides until the soot rubbed off.  This revealed that the sensor is white in color and looks like a circuit board with flat components printed on it. 

Needless to say if upon initial inspection one sees no debris coating, cleaning the sensor may be unnecessary and the root cause of the problem may simply be a failed sensor or other root causes of what led one to clean the sensor.

I also sprayed and swab cleaned another smaller pass-through on the stalk closer to its base where it mounts to its dedicated duct.

I put the sensor back in my car and the light was out! I ran the codes and no sensor code was listed.

The key to success seemed to be using swabs to clean the sensor, as the debris coating on the sensor will not simply wash off from spraying. 

There are two methods to remove and reinstall the sensor for cleaning. 

• If access to the sensor stalk's mounting screws on each side of its electrical connector is good, using a T20 Torx Security bit, the style with the hole in the center, will allow one to remove the two screws holding the sensor to its dedicated duct.
  
  
  This method avoids the need to remove the air-box and detach the rubber intake duct from the sensor's dedicated duct making the job quick and easy.

• The alternative is to remove the sensor and its dedicated duct together in one piece. This method involved removing the air filter housing and detaching the sensor's dedicated duct from the intake duct by loosening a hose clamp. The tricky part in this greater disassembly method is in the reinstallation, here is how to do it with a minimum of aggravation:
• First, put a 7mm socket with flex joint and long extension together. Tape over the tool’s parts so they do not pull apart easily and the flex joint wants to stay straight

• Pre-position the assembled tool above onto the intake duct's clamp ring tightening nut and leave it in position;
• Then place the MAF sensor' duct in its approximate final installed position, not attached on its ends or wire. Put the air filter housing in its approximate installed position. Then while in-place bayonet the sensor's duct housing to the air filter housing.
• Attach the wires to the sensor and the temperature sensor on the air filter housing.
• Next work the air sensor duct and filter housing as a unit into the intake rubber duct on the left and tighten the 7mm socket you pre-positioned above. During this process also orient the vent hose leading to the bottom front of the filter housing and position the clamp ring on this hose for later tightening.
• If the 7mm socket has fallen off the clamp ring you will need to go back and reposition it.
• Then align the air filter housing on its rubber mounting stalks located under the housing and tighten the clamp on the vent hose to the housing.

Use a very small amount of wax-like petroleum lubricant on the hoses, ducts, and housings so things slip together easily. I used the absolute minimum of this to avoid contamination of the Sensor element. I did not use rubber, plastic, or silicone lubricant as the effect of these on the sensor is unknown to me.