If your Mazda 626 Air Flow Meter keeps failing the issue is most likely to much oil on a Mazda performance air filter, or to much blow by from the 626 engine.
Use only Mazda OE quality replacement Catalytic Converters to keek your Mazda 626 in the best running condition. DriveWire sells only California legal 626 OBD-II Converters.
If your Mazda 626 failed the emissions test due to high NOX, the EGR Valve is most likely the issue. If your Mazda is running rough or has poor fuel mileage, replace the 626 EGR Valve and gasket.
Replace your faulty Mazda 626 Mass Air Flow Sensor with a Genuine or OE Bosch Unit to keep your Mazda running like new.
The Mazda 626 Oxygen sensor is a critical part of the emmision control system and should be replaced as soon as it fails. Make sure to check the Mazda 626 diagnosics codes for proper replacement of the O2 Sensor.