2004 Alero 3.4L Mass Air Flow

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2004 Alero 3.4L Mass Air Flow

Unread post by whatever333 » Fri Oct 09, 2015 9:33 pm

Can you clean the Mass Air Flow Sensor or do you have to buy new one? Also low coolant light comes on periodically but when I check water level it is fine. Why is it doing that?


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Re: 2004 Alero 3.4L Mass Air Flow

Unread post by carriedi » Sat Oct 10, 2015 1:35 am

yes, you can clean the MAF sensor. the mass air flow sensor has resistors the the computer monitors as air passes through. the MAF gets battery power from the pcm/ign fuse in the underhood fuse block. it is grounded by the PCM. the current that passes through the resistors in the MAF are monitored by the yellow wire. The sensor heats the wire resistors and works by the wind chill affect of the air rushing by the wire. The amount of air that moves by the sensor will cool the wire. As the wire cools the resistance changes and changes the current needed to heat the wire.

Over time, Tiny particles will collect on the wire. As the particles build up they act as insulators that shield the sensor from the wind chill factor. Eventually, if it gets bad enough, you MAF and fuel trim calculated by the PCM won't match up with what the O2 sensor sees in the exhaust. So, you would get lean codes.

you cam clean the MAF sensor heated wires with a good spray cleaner. Do not touch the wires. They are very thin wires and easily broken. Just remove the sensor and spray the sensor wires until they look clean. Spray in the direction that the air flows through the sensor. Some cleaners work better than others. When the resistors look clean just wait a couple minutes for everything to dry and they reinstall the MAF.

while you clean the MAF you may as well clean the throttle body where the throttle plate closes. Coking builds up where the air goes by while the throttle is closed. It closes off the minimum flow that the idle air control adjusts for.That build up raises the IAC counts as it slowly chokes off the closed throttle air.

the parts of the MAF to clean are circled in red.
gm maf.jpg
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