How to Clean Your 1998 Mazda 626 LX's Mass Air Flow Sensor

Mass airflow sensors like those used in the Mazda 626 (and it's Ford Contour cousin) use a heated wire to determine airflow. That heated wire hangs down inside a housing tube, directly in line with the airstream coming through the air filter box and into the vehicle's engine. Air passing over the hot wire cools it down, and this changes the wire's electrical resistance in a predictable way. The car's computer reads that change in resistance and uses it to extrapolate airflow. Buildup on the MAF will keep heat in the wire and give a false signal; fortunately, cleaning a MAF sensor is a quick, easy job provided that you have the right tools.

Instructions

1

Identify your MAF sensor -- it is sitting on top of the metal housing that bolts to the air box. The sensor itself is inside the MAF sensor housing, bolted to the airbox; from the top, you'll see a black, rectangular box with a wiring harness connected to it. Unplug that wiring harness.

2

Remove the two star-bit safety screws at the corners of the MAF sensor box. Mazda installs these tamper-proof "safety screws" specifically to make removal impossible for ill-equipped shade-tree mechanics, so you'll need to run out and get the correct bit if you don't have one.

3

Pull up on the MAF sensor very slowly and carefully. The sensor wire assembly itself dangles down into the tube, and it's very easy to damage during removal and installation. Once you have the sensor out, hold it by the black sensor box, with the sensor wire itself pointed downward.

4

Spray the sensor wire -- at a downward angle to avoid hitting the plastic sensor box -- with a dedicated MAF sensor cleaner or brake cleaner. Do not use carburetor cleaner -- carb cleaner leaves an oil residue behind, which will bake onto the MAF when the wire heats up. MAF sensor cleaner is best, as brake cleaner can eat into plastic. If you're using it, then wrap the plastic sensor box with a thick dish-rag while you clean the metal wire.

5

Push the MAF sensor back into the sensor housing, just as it came out. Again, go slow and be very cautious when installing it. Tighten the star-head screws very lightly; a screwdriver with a small-diameter handle might work best to prevent over-tightening. The screws aren't particularly load-bearing, so a couple of foot-pounds of torque is all you'll need.