MAF Sensor Replacement

MAF Sensor in the car
The Check Engine light on my wife’s 1999 Buick Regal 3.8L came on. After resetting it came on again in a day or so. It had been changed just about a year ago. It came on whenever it was moist outside. My first look at revealed that the cover was lifted. Perhaps moisture was getting in through lifted cover. I put some Goop on it and hoped that it would settle down.
After a couple of days, the light was on again. Time for a replacement. My son did some Internet research and found that someone who had re-replaced the rebuilt unit with a “new” unit and had good results. I got the new OEM part.
Installation of the MAF is straightforward. The only hitch is as a high value part, it has security Torx screws so you are going to need that special driver.

Disconnect the battery. Carefully release the locks on the plug and pull the plug. There are water seals inside so it can be a bit stiff. Slow and steady. Then remove the screws in the corners. Remove the sensor by lifting straight out. Install the new unit. Start, then tighten the screws. Replace the plug. Reconnect the battery.

MAF Sensor business end

The Mass Air Flow (MAF) sensor tells the engine control computer how much air is flowing into the engine. The computer uses this along with other inputs to decide mixture and other controls.

Under the MAF sensor lid

Since I bought the new unit, there was no need to return the “core” as with a rebuilt part. So What Is In There? The second picture shows the part of the MAF sensor that is in the intake duct. The air goes through the hole and by that horizontal bit. That is actually a “hot wire” sensor. Heated by a current, its resistance varies by temperature. The more air that flows by the cooler the hot wire and so its resistance comes down. You can see that under the lid there is a fairly sophisticated circuit associated with this device.

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